watch_queue_clear() has a comment stating that setting ->defunct to true
preventing new additions as well as preventing notifications. Whilst
the latter is true, the first bit is superfluous since at the time this
function is called, the pipe cannot be accessed to add new event
sources.
Remove the "new additions" bit from the comment.
Fixes: c73be61ced ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There's nothing to synchronise post_one_notification() versus
pipe_read(). Whilst posting is done under pipe->rd_wait.lock, the
reader only takes pipe->mutex which cannot bar notification posting as
that may need to be made from contexts that cannot sleep.
Fix this by setting pipe->head with a barrier in post_one_notification()
and reading pipe->head with a barrier in pipe_read().
If that's not sufficient, the rd_wait.lock will need to be taken,
possibly in a ->confirm() op so that it only applies to notifications.
The lock would, however, have to be dropped before copy_page_to_iter()
is invoked.
Fixes: c73be61ced ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently, watch_queue_set_size() sets the number of notes available in
wqueue->nr_notes according to the number of notes allocated, but sets
the size of the bitmap to the unrounded number of notes originally asked
for.
Fix this by setting the bitmap size to the number of notes we're
actually going to make available (ie. the number allocated).
Fixes: c73be61ced ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Use bitmap_alloc() to simplify code, improve the semantic and reduce
some open-coded arithmetic in allocator arguments.
Also change a memset(0xff) into an equivalent bitmap_fill() to keep
consistency.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The pipe ring size must always be a power of 2 as the head and tail
pointers are masked off by AND'ing with the size of the ring - 1.
watch_queue_set_size(), however, lets you specify any number of notes
between 1 and 511. This number is passed through to pipe_resize_ring()
without checking/forcing its alignment.
Fix this by rounding the number of slots required up to the nearest
power of two. The request is meant to guarantee that at least that many
notifications can be generated before the queue is full, so rounding
down isn't an option, but, alternatively, it may be better to give an
error if we aren't allowed to allocate that much ring space.
Fixes: c73be61ced ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When a pipe ring descriptor points to a notification message, the
refcount on the backing page is incremented by the generic get function,
but the release function, which marks the bitmap, doesn't drop the page
ref.
Fix this by calling generic_pipe_buf_release() at the end of
watch_queue_pipe_buf_release().
Fixes: c73be61ced ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
In watch_queue_set_filter(), there are a couple of places where we check
that the filter type value does not exceed what the type_filter bitmap
can hold. One place calculates the number of bits by:
if (tf[i].type >= sizeof(wfilter->type_filter) * 8)
which is fine, but the second does:
if (tf[i].type >= sizeof(wfilter->type_filter) * BITS_PER_LONG)
which is not. This can lead to a couple of out-of-bounds writes due to
a too-large type:
(1) __set_bit() on wfilter->type_filter
(2) Writing more elements in wfilter->filters[] than we allocated.
Fix this by just using the proper WATCH_TYPE__NR instead, which is the
number of types we actually know about.
The bug may cause an oops looking something like:
BUG: KASAN: slab-out-of-bounds in watch_queue_set_filter+0x659/0x740
Write of size 4 at addr ffff88800d2c66bc by task watch_queue_oob/611
...
Call Trace:
<TASK>
dump_stack_lvl+0x45/0x59
print_address_description.constprop.0+0x1f/0x150
...
kasan_report.cold+0x7f/0x11b
...
watch_queue_set_filter+0x659/0x740
...
__x64_sys_ioctl+0x127/0x190
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
Allocated by task 611:
kasan_save_stack+0x1e/0x40
__kasan_kmalloc+0x81/0xa0
watch_queue_set_filter+0x23a/0x740
__x64_sys_ioctl+0x127/0x190
do_syscall_64+0x43/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xae
The buggy address belongs to the object at ffff88800d2c66a0
which belongs to the cache kmalloc-32 of size 32
The buggy address is located 28 bytes inside of
32-byte region [ffff88800d2c66a0, ffff88800d2c66c0)
Fixes: c73be61ced ("pipe: Add general notification queue support")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
- Fix sorting on old "cpu" value in histograms
- Fix return value of __setup() boot parameter handlers.
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Merge tag 'trace-v5.17-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
- Fix sorting on old "cpu" value in histograms
- Fix return value of __setup() boot parameter handlers
* tag 'trace-v5.17-rc5' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
tracing: Fix return value of __setup handlers
tracing/histogram: Fix sorting on old "cpu" value
Merge misc fixes from Andrew Morton:
"8 patches.
Subsystems affected by this patch series: mm (hugetlb, pagemap, and
userfaultfd), memfd, selftests, and kconfig"
* emailed patches from Andrew Morton <akpm@linux-foundation.org>:
configs/debug: set CONFIG_DEBUG_INFO=y properly
proc: fix documentation and description of pagemap
kselftest/vm: fix tests build with old libc
memfd: fix F_SEAL_WRITE after shmem huge page allocated
mm: fix use-after-free when anon vma name is used after vma is freed
mm: prevent vm_area_struct::anon_name refcount saturation
mm: refactor vm_area_struct::anon_vma_name usage code
selftests/vm: cleanup hugetlb file after mremap test
CONFIG_DEBUG_INFO can't be set by user directly, so set
CONFIG_DEBUG_INFO_DWARF_TOOLCHAIN_DEFAULT=y instead.
Otherwise, we end up with no debuginfo in vmlinux which is a big no-no
for kernel debugging.
Link: https://lkml.kernel.org/r/20220301202920.18488-1-quic_qiancai@quicinc.com
Signed-off-by: Qian Cai <quic_qiancai@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Merge tag 'block-5.17-2022-03-04' of git://git.kernel.dk/linux-block
Pull block fix from Jens Axboe:
"Just a small UAF fix for blktrace"
* tag 'block-5.17-2022-03-04' of git://git.kernel.dk/linux-block:
blktrace: fix use after free for struct blk_trace
__setup() handlers should generally return 1 to indicate that the
boot options have been handled.
Using invalid option values causes the entire kernel boot option
string to be reported as Unknown and added to init's environment
strings, polluting it.
Unknown kernel command line parameters "BOOT_IMAGE=/boot/bzImage-517rc6
kprobe_event=p,syscall_any,$arg1 trace_options=quiet
trace_clock=jiffies", will be passed to user space.
Run /sbin/init as init process
with arguments:
/sbin/init
with environment:
HOME=/
TERM=linux
BOOT_IMAGE=/boot/bzImage-517rc6
kprobe_event=p,syscall_any,$arg1
trace_options=quiet
trace_clock=jiffies
Return 1 from the __setup() handlers so that init's environment is not
polluted with kernel boot options.
Link: lore.kernel.org/r/64644a2f-4a20-bab3-1e15-3b2cdd0defe3@omprussia.ru
Link: https://lkml.kernel.org/r/20220303031744.32356-1-rdunlap@infradead.org
Cc: stable@vger.kernel.org
Fixes: 7bcfaf54f5 ("tracing: Add trace_options kernel command line parameter")
Fixes: e1e232ca6b ("tracing: Add trace_clock=<clock> kernel parameter")
Fixes: 970988e19e ("tracing/kprobe: Add kprobe_event= boot parameter")
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Reported-by: Igor Zhbanov <i.zhbanov@omprussia.ru>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Pull ucounts fix from Eric Biederman:
"Etienne Dechamps recently found a regression caused by enforcing
RLIMIT_NPROC for root where the rlimit was not previously enforced.
Michal Koutný had previously pointed out the inconsistency in
enforcing the RLIMIT_NPROC that had been on the root owned process
after the root user creates a user namespace.
Which makes the fix for the regression simply removing the
inconsistency"
* 'ucount-rlimit-fixes-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
ucounts: Fix systemd LimitNPROC with private users regression
When trying to add a histogram against an event with the "cpu" field, it
was impossible due to "cpu" being a keyword to key off of the running CPU.
So to fix this, it was changed to "common_cpu" to match the other generic
fields (like "common_pid"). But since some scripts used "cpu" for keying
off of the CPU (for events that did not have "cpu" as a field, which is
most of them), a backward compatibility trick was added such that if "cpu"
was used as a key, and the event did not have "cpu" as a field name, then
it would fallback and switch over to "common_cpu".
This fix has a couple of subtle bugs. One was that when switching over to
"common_cpu", it did not change the field name, it just set a flag. But
the code still found a "cpu" field. The "cpu" field is used for filtering
and is returned when the event does not have a "cpu" field.
This was found by:
# cd /sys/kernel/tracing
# echo hist:key=cpu,pid:sort=cpu > events/sched/sched_wakeup/trigger
# cat events/sched/sched_wakeup/hist
Which showed the histogram unsorted:
{ cpu: 19, pid: 1175 } hitcount: 1
{ cpu: 6, pid: 239 } hitcount: 2
{ cpu: 23, pid: 1186 } hitcount: 14
{ cpu: 12, pid: 249 } hitcount: 2
{ cpu: 3, pid: 994 } hitcount: 5
Instead of hard coding the "cpu" checks, take advantage of the fact that
trace_event_field_field() returns a special field for "cpu" and "CPU" if
the event does not have "cpu" as a field. This special field has the
"filter_type" of "FILTER_CPU". Check that to test if the returned field is
of the CPU type instead of doing the string compare.
Also, fix the sorting bug by testing for the hist_field flag of
HIST_FIELD_FL_CPU when setting up the sort routine. Otherwise it will use
the special CPU field to know what compare routine to use, and since that
special field does not have a size, it returns tracing_map_cmp_none.
Cc: stable@vger.kernel.org
Fixes: 1e3bac71c5 ("tracing/histogram: Rename "cpu" to "common_cpu"")
Reported-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
- fix a swiotlb info leak (Halil Pasic)
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Merge tag 'dma-mapping-5.17-1' of git://git.infradead.org/users/hch/dma-mapping
Pull dma-mapping fix from Christoph Hellwig:
- fix a swiotlb info leak (Halil Pasic)
* tag 'dma-mapping-5.17-1' of git://git.infradead.org/users/hch/dma-mapping:
swiotlb: fix info leak with DMA_FROM_DEVICE
- rtla (Real-Time Linux Analysis tool): fix typo in man page
- rtla: Update API -e to -E before it is released
- rlla: Error message fix and memory leak fix
- Partially uninline trace event soft disable to shrink text
- Fix function graph start up test
- Have triggers affect the trace instance they are in and not top level
- Have osnoise sleep in the units it says it uses
- Remove unused ftrace stub function
- Remove event probe redundant info from event in the buffer
- Fix group ownership setting in tracefs
- Ensure trace buffer is minimum size to prevent crashes
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Merge tag 'trace-v5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace
Pull tracing fixes from Steven Rostedt:
- rtla (Real-Time Linux Analysis tool):
- fix typo in man page
- Update API -e to -E before it is released
- Error message fix and memory leak fix
- Partially uninline trace event soft disable to shrink text
- Fix function graph start up test
- Have triggers affect the trace instance they are in and not top level
- Have osnoise sleep in the units it says it uses
- Remove unused ftrace stub function
- Remove event probe redundant info from event in the buffer
- Fix group ownership setting in tracefs
- Ensure trace buffer is minimum size to prevent crashes
* tag 'trace-v5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-trace:
rtla/osnoise: Fix error message when failing to enable trace instance
rtla/osnoise: Free params at the exit
rtla/hist: Make -E the short version of --entries
tracing: Fix selftest config check for function graph start up test
tracefs: Set the group ownership in apply_options() not parse_options()
tracing/osnoise: Make osnoise_main to sleep for microseconds
ftrace: Remove unused ftrace_startup_enable() stub
tracing: Ensure trace buffer is at least 4096 bytes large
tracing: Uninline trace_trigger_soft_disabled() partly
eprobes: Remove redundant event type information
tracing: Have traceon and traceoff trigger honor the instance
tracing: Dump stacktrace trigger to the corresponding instance
rtla: Fix systme -> system typo on man page
osnoise's runtime and period are in the microseconds scale, but it is
currently sleeping in the millisecond's scale. This behavior roots in the
usage of hwlat as the skeleton for osnoise.
Make osnoise to sleep in the microseconds scale. Also, move the sleep to
a specialized function.
Link: https://lkml.kernel.org/r/302aa6c7bdf2d131719b22901905e9da122a11b2.1645197336.git.bristot@kernel.org
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
When building with clang + CONFIG_DYNAMIC_FTRACE=n + W=1, there is a
warning:
kernel/trace/ftrace.c:7194:20: error: unused function 'ftrace_startup_enable' [-Werror,-Wunused-function]
static inline void ftrace_startup_enable(int command) { }
^
1 error generated.
Clang warns on instances of static inline functions in .c files with W=1
after commit 6863f5643d ("kbuild: allow Clang to find unused static
inline functions for W=1 build").
The ftrace_startup_enable() stub has been unused since
commit e1effa0144 ("ftrace: Annotate the ops operation on update"),
where its use outside of the CONFIG_DYNAMIC_TRACE section was replaced
by ftrace_startup_all(). Remove it to resolve the warning.
Link: https://lkml.kernel.org/r/20220214192847.488166-1-nathan@kernel.org
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
On a powerpc32 build with CONFIG_CC_OPTIMISE_FOR_SIZE, the inline
keyword is not honored and trace_trigger_soft_disabled() appears
approx 50 times in vmlinux.
Adding -Winline to the build, the following message appears:
./include/linux/trace_events.h:712:1: error: inlining failed in call to 'trace_trigger_soft_disabled': call is unlikely and code size would grow [-Werror=inline]
That function is rather big for an inlined function:
c003df60 <trace_trigger_soft_disabled>:
c003df60: 94 21 ff f0 stwu r1,-16(r1)
c003df64: 7c 08 02 a6 mflr r0
c003df68: 90 01 00 14 stw r0,20(r1)
c003df6c: bf c1 00 08 stmw r30,8(r1)
c003df70: 83 e3 00 24 lwz r31,36(r3)
c003df74: 73 e9 01 00 andi. r9,r31,256
c003df78: 41 82 00 10 beq c003df88 <trace_trigger_soft_disabled+0x28>
c003df7c: 38 60 00 00 li r3,0
c003df80: 39 61 00 10 addi r11,r1,16
c003df84: 4b fd 60 ac b c0014030 <_rest32gpr_30_x>
c003df88: 73 e9 00 80 andi. r9,r31,128
c003df8c: 7c 7e 1b 78 mr r30,r3
c003df90: 41 a2 00 14 beq c003dfa4 <trace_trigger_soft_disabled+0x44>
c003df94: 38 c0 00 00 li r6,0
c003df98: 38 a0 00 00 li r5,0
c003df9c: 38 80 00 00 li r4,0
c003dfa0: 48 05 c5 f1 bl c009a590 <event_triggers_call>
c003dfa4: 73 e9 00 40 andi. r9,r31,64
c003dfa8: 40 82 00 28 bne c003dfd0 <trace_trigger_soft_disabled+0x70>
c003dfac: 73 ff 02 00 andi. r31,r31,512
c003dfb0: 41 82 ff cc beq c003df7c <trace_trigger_soft_disabled+0x1c>
c003dfb4: 80 01 00 14 lwz r0,20(r1)
c003dfb8: 83 e1 00 0c lwz r31,12(r1)
c003dfbc: 7f c3 f3 78 mr r3,r30
c003dfc0: 83 c1 00 08 lwz r30,8(r1)
c003dfc4: 7c 08 03 a6 mtlr r0
c003dfc8: 38 21 00 10 addi r1,r1,16
c003dfcc: 48 05 6f 6c b c0094f38 <trace_event_ignore_this_pid>
c003dfd0: 38 60 00 01 li r3,1
c003dfd4: 4b ff ff ac b c003df80 <trace_trigger_soft_disabled+0x20>
However it is located in a hot path so inlining it is important.
But forcing inlining of the entire function by using __always_inline
leads to increasing the text size by approx 20 kbytes.
Instead, split the fonction in two parts, one part with the likely
fast path, flagged __always_inline, and a second part out of line.
With this change, on a powerpc32 with CONFIG_CC_OPTIMISE_FOR_SIZE
vmlinux text increases by only 1,4 kbytes, which is partly
compensated by a decrease of vmlinux data by 7 kbytes.
On ppc64_defconfig which has CONFIG_CC_OPTIMISE_FOR_SPEED, this
change reduces vmlinux text by more than 30 kbytes.
Link: https://lkml.kernel.org/r/69ce0986a52d026d381d612801d978aa4f977460.1644563295.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Currently, the event probes save the type of the event they are attached
to when recording the event. For example:
# echo 'e:switch sched/sched_switch prev_state=$prev_state prev_prio=$prev_prio next_pid=$next_pid next_prio=$next_prio' > dynamic_events
# cat events/eprobes/switch/format
name: switch
ID: 1717
format:
field:unsigned short common_type; offset:0; size:2; signed:0;
field:unsigned char common_flags; offset:2; size:1; signed:0;
field:unsigned char common_preempt_count; offset:3; size:1; signed:0;
field:int common_pid; offset:4; size:4; signed:1;
field:unsigned int __probe_type; offset:8; size:4; signed:0;
field:u64 prev_state; offset:12; size:8; signed:0;
field:u64 prev_prio; offset:20; size:8; signed:0;
field:u64 next_pid; offset:28; size:8; signed:0;
field:u64 next_prio; offset:36; size:8; signed:0;
print fmt: "(%u) prev_state=0x%Lx prev_prio=0x%Lx next_pid=0x%Lx next_prio=0x%Lx", REC->__probe_type, REC->prev_state, REC->prev_prio, REC->next_pid, REC->next_prio
The __probe_type adds 4 bytes to every event.
One of the reasons for creating eprobes is to limit what is traced in an
event to be able to limit what is written into the ring buffer. Having
this redundant 4 bytes to every event takes away from this.
The event that is recorded can be retrieved from the event probe itself,
that is available when the trace is happening. For user space tools, it
could simply read the dynamic_event file to find the event they are for.
So there is really no reason to write this information into the ring
buffer for every event.
Link: https://lkml.kernel.org/r/20220218190057.2f5a19a8@gandalf.local.home
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Reviewed-by: Joel Fernandes <joel@joelfernandes.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
If a trigger is set on an event to disable or enable tracing within an
instance, then tracing should be disabled or enabled in the instance and
not at the top level, which is confusing to users.
Link: https://lkml.kernel.org/r/20220223223837.14f94ec3@rorschach.local.home
Cc: stable@vger.kernel.org
Fixes: ae63b31e4d ("tracing: Separate out trace events from global variables")
Tested-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Long story short recursively enforcing RLIMIT_NPROC when it is not
enforced on the process that creates a new user namespace, causes
currently working code to fail. There is no reason to enforce
RLIMIT_NPROC recursively when we don't enforce it normally so update
the code to detect this case.
I would like to simply use capable(CAP_SYS_RESOURCE) to detect when
RLIMIT_NPROC is not enforced upon the caller. Unfortunately because
RLIMIT_NPROC is charged and checked for enforcement based upon the
real uid, using capable() which is euid based is inconsistent with reality.
Come as close as possible to testing for capable(CAP_SYS_RESOURCE) by
testing for when the real uid would match the conditions when
CAP_SYS_RESOURCE would be present if the real uid was the effective
uid.
Reported-by: Etienne Dechamps <etienne@edechamps.fr>
Link: https://bugzilla.kernel.org/show_bug.cgi?id=215596
Link: https://lkml.kernel.org/r/e9589141-cfeb-90cd-2d0e-83a62787239a@edechamps.fr
Link: https://lkml.kernel.org/r/87sfs8jmpz.fsf_-_@email.froward.int.ebiederm.org
Cc: stable@vger.kernel.org
Fixes: 21d1c5e386 ("Reimplement RLIMIT_NPROC on top of ucounts")
Reviewed-by: Kees Cook <keescook@chromium.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
The stacktrace event trigger is not dumping the stacktrace to the instance
where it was enabled, but to the global "instance."
Use the private_data, pointing to the trigger file, to figure out the
corresponding trace instance, and use it in the trigger action, like
snapshot_trigger does.
Link: https://lkml.kernel.org/r/afbb0b4f18ba92c276865bc97204d438473f4ebc.1645396236.git.bristot@kernel.org
Cc: stable@vger.kernel.org
Fixes: ae63b31e4d ("tracing: Separate out trace events from global variables")
Reviewed-by: Tom Zanussi <zanussi@kernel.org>
Tested-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Daniel Bristot de Oliveira <bristot@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Current release - regressions:
- bpf: fix crash due to out of bounds access into reg2btf_ids
- mvpp2: always set port pcs ops, avoid null-deref
- eth: marvell: fix driver load from initrd
- eth: intel: revert "Fix reset bw limit when DCB enabled with 1 TC"
Current release - new code bugs:
- mptcp: fix race in overlapping signal events
Previous releases - regressions:
- xen-netback: revert hotplug-status changes causing devices to
not be configured
- dsa:
- avoid call to __dev_set_promiscuity() while rtnl_mutex isn't held
- fix panic when removing unoffloaded port from bridge
- dsa: microchip: fix bridging with more than two member ports
Previous releases - always broken:
- bpf:
- fix crash due to incorrect copy_map_value when both spin lock
and timer are present in a single value
- fix a bpf_timer initialization issue with clang
- do not try bpf_msg_push_data with len 0
- add schedule points in batch ops
- nf_tables:
- unregister flowtable hooks on netns exit
- correct flow offload action array size
- fix a couple of memory leaks
- vsock: don't check owner in vhost_vsock_stop() while releasing
- gso: do not skip outer ip header in case of ipip and net_failover
- smc: use a mutex for locking "struct smc_pnettable"
- openvswitch: fix setting ipv6 fields causing hw csum failure
- mptcp: fix race in incoming ADD_ADDR option processing
- sysfs: add check for netdevice being present to speed_show
- sched: act_ct: fix flow table lookup after ct clear or switching
zones
- eth: intel: fixes for SR-IOV forwarding offloads
- eth: broadcom: fixes for selftests and error recovery
- eth: mellanox: flow steering and SR-IOV forwarding fixes
Misc:
- make __pskb_pull_tail() & pskb_carve_frag_list() drop_monitor
friends not report freed skbs as drops
- force inlining of checksum functions in net/checksum.h
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'net-5.17-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net
Pull networking fixes from Jakub Kicinski:
"Including fixes from bpf and netfilter.
Current release - regressions:
- bpf: fix crash due to out of bounds access into reg2btf_ids
- mvpp2: always set port pcs ops, avoid null-deref
- eth: marvell: fix driver load from initrd
- eth: intel: revert "Fix reset bw limit when DCB enabled with 1 TC"
Current release - new code bugs:
- mptcp: fix race in overlapping signal events
Previous releases - regressions:
- xen-netback: revert hotplug-status changes causing devices to not
be configured
- dsa:
- avoid call to __dev_set_promiscuity() while rtnl_mutex isn't
held
- fix panic when removing unoffloaded port from bridge
- dsa: microchip: fix bridging with more than two member ports
Previous releases - always broken:
- bpf:
- fix crash due to incorrect copy_map_value when both spin lock
and timer are present in a single value
- fix a bpf_timer initialization issue with clang
- do not try bpf_msg_push_data with len 0
- add schedule points in batch ops
- nf_tables:
- unregister flowtable hooks on netns exit
- correct flow offload action array size
- fix a couple of memory leaks
- vsock: don't check owner in vhost_vsock_stop() while releasing
- gso: do not skip outer ip header in case of ipip and net_failover
- smc: use a mutex for locking "struct smc_pnettable"
- openvswitch: fix setting ipv6 fields causing hw csum failure
- mptcp: fix race in incoming ADD_ADDR option processing
- sysfs: add check for netdevice being present to speed_show
- sched: act_ct: fix flow table lookup after ct clear or switching
zones
- eth: intel: fixes for SR-IOV forwarding offloads
- eth: broadcom: fixes for selftests and error recovery
- eth: mellanox: flow steering and SR-IOV forwarding fixes
Misc:
- make __pskb_pull_tail() & pskb_carve_frag_list() drop_monitor
friends not report freed skbs as drops
- force inlining of checksum functions in net/checksum.h"
* tag 'net-5.17-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net: (85 commits)
net: mv643xx_eth: process retval from of_get_mac_address
ping: remove pr_err from ping_lookup
Revert "i40e: Fix reset bw limit when DCB enabled with 1 TC"
openvswitch: Fix setting ipv6 fields causing hw csum failure
ipv6: prevent a possible race condition with lifetimes
net/smc: Use a mutex for locking "struct smc_pnettable"
bnx2x: fix driver load from initrd
Revert "xen-netback: Check for hotplug-status existence before watching"
Revert "xen-netback: remove 'hotplug-status' once it has served its purpose"
net/mlx5e: Fix VF min/max rate parameters interchange mistake
net/mlx5e: Add missing increment of count
net/mlx5e: MPLSoUDP decap, fix check for unsupported matches
net/mlx5e: Fix MPLSoUDP encap to use MPLS action information
net/mlx5e: Add feature check for set fec counters
net/mlx5e: TC, Skip redundant ct clear actions
net/mlx5e: TC, Reject rules with forward and drop actions
net/mlx5e: TC, Reject rules with drop and modify hdr action
net/mlx5e: kTLS, Use CHECKSUM_UNNECESSARY for device-offloaded packets
net/mlx5e: Fix wrong return value on ioctl EEPROM query failure
net/mlx5: Fix possible deadlock on rule deletion
...
Pull cgroup fixes from Tejun Heo:
- Fix for a subtle bug in the recent release_agent permission check
update
- Fix for a long-standing race condition between cpuset and cpu hotplug
- Comment updates
* 'for-5.17-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cpuset: Fix kernel-doc
cgroup-v1: Correct privileges check in release_agent writes
cgroup: clarify cgroup_css_set_fork()
cgroup/cpuset: Fix a race between cpuset_attach() and cpu hotplug
Fix the following W=1 kernel warnings:
kernel/cgroup/cpuset.c:3718: warning: expecting prototype for
cpuset_memory_pressure_bump(). Prototype was for
__cpuset_memory_pressure_bump() instead.
kernel/cgroup/cpuset.c:3568: warning: expecting prototype for
cpuset_node_allowed(). Prototype was for __cpuset_node_allowed()
instead.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The idea is to check: a) the owning user_ns of cgroup_ns, b)
capabilities in init_user_ns.
The commit 24f6008564 ("cgroup-v1: Require capabilities to set
release_agent") got this wrong in the write handler of release_agent
since it checked user_ns of the opener (may be different from the owning
user_ns of cgroup_ns).
Secondly, to avoid possibly confused deputy, the capability of the
opener must be checked.
Fixes: 24f6008564 ("cgroup-v1: Require capabilities to set release_agent")
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/stable/20220216121142.GB30035@blackbody.suse.cz/
Signed-off-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Masami Ichikawa(CIP) <masami.ichikawa@cybertrust.co.jp>
Signed-off-by: Tejun Heo <tj@kernel.org>
With recent fixes for the permission checking when moving a task into a cgroup
using a file descriptor to a cgroup's cgroup.procs file and calling write() it
seems a good idea to clarify CLONE_INTO_CGROUP permission checking with a
comment.
Cc: Tejun Heo <tj@kernel.org>
Cc: <cgroups@vger.kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Tejun Heo <tj@kernel.org>
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Merge tag 'pidfd.v5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull pidfd fix from Christian Brauner:
"This fixes a problem reported by lockdep when installing a pidfd via
fd_install() with siglock and the tasklisk write lock held in
copy_process() when calling clone()/clone3() with CLONE_PIDFD.
Originally a pidfd was created prior to holding any of these locks but
this required a call to ksys_close(). So quite some time ago in
6fd2fe494b ("copy_process(): don't use ksys_close() on cleanups") we
switched to a get_unused_fd_flags() + fd_install() model.
As part of that we moved fd_install() as late as possible. This was
done for two main reasons. First, because we needed to ensure that we
call fd_install() past the point of no return as once that's called
the fd is live in the task's file table. Second, because we tried to
ensure that the fd is visible in /proc/<pid>/fd/<pidfd> right when the
task is visible.
This fix moves the fd_install() to an even later point which means
that a task will be visible in proc while the pidfd isn't yet under
/proc/<pid>/fd/<pidfd>.
While this is a user visible change it's very unlikely that this will
have any impact. Nobody should be relying on that and if they do we
need to come up with something better but again, it's doubtful this is
relevant"
* tag 'pidfd.v5.17-rc4' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux:
copy_process(): Move fd_install() out of sighand->siglock critical section
Pull ucounts fixes from Eric Biederman:
"Michal Koutný recently found some bugs in the enforcement of
RLIMIT_NPROC in the recent ucount rlimit implementation.
In this set of patches I have developed a very conservative approach
changing only what is necessary to fix the bugs that I can see
clearly. Cleanups and anything that is making the code more consistent
can follow after we have the code working as it has historically.
The problem is not so much inconsistencies (although those exist) but
that it is very difficult to figure out what the code should be doing
in the case of RLIMIT_NPROC.
All other rlimits are only enforced where the resource is acquired
(allocated). RLIMIT_NPROC by necessity needs to be enforced in an
additional location, and our current implementation stumbled it's way
into that implementation"
* 'ucount-rlimit-fixes-for-v5.17' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace:
ucounts: Handle wrapping in is_ucounts_overlimit
ucounts: Move RLIMIT_NPROC handling after set_user
ucounts: Base set_cred_ucounts changes on the real user
ucounts: Enforce RLIMIT_NPROC not RLIMIT_NPROC+1
rlimit: Fix RLIMIT_NPROC enforcement failure caused by capability calls in set_user
Where commit 4ef0c5c6b5 ("kernel/sched: Fix sched_fork() access an
invalid sched_task_group") fixed a fork race vs cgroup, it opened up a
race vs syscalls by not placing the task on the runqueue before it
gets exposed through the pidhash.
Commit 13765de814 ("sched/fair: Fix fault in reweight_entity") is
trying to fix a single instance of this, instead fix the whole class
of issues, effectively reverting this commit.
Fixes: 4ef0c5c6b5 ("kernel/sched: Fix sched_fork() access an invalid sched_task_group")
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Tadeusz Struk <tadeusz.struk@linaro.org>
Tested-by: Zhang Qiao <zhangqiao22@huawei.com>
Tested-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lkml.kernel.org/r/YgoeCbwj5mbCR0qA@hirez.programming.kicks-ass.net
Alexei Starovoitov says:
====================
pull-request: bpf 2022-02-17
We've added 8 non-merge commits during the last 7 day(s) which contain
a total of 8 files changed, 119 insertions(+), 15 deletions(-).
The main changes are:
1) Add schedule points in map batch ops, from Eric.
2) Fix bpf_msg_push_data with len 0, from Felix.
3) Fix crash due to incorrect copy_map_value, from Kumar.
4) Fix crash due to out of bounds access into reg2btf_ids, from Kumar.
5) Fix a bpf_timer initialization issue with clang, from Yonghong.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
bpf: Add schedule points in batch ops
bpf: Fix crash due to out of bounds access into reg2btf_ids.
selftests: bpf: Check bpf_msg_push_data return value
bpf: Fix a bpf_timer initialization issue
bpf: Emit bpf_timer in vmlinux BTF
selftests/bpf: Add test for bpf_timer overwriting crash
bpf: Fix crash due to incorrect copy_map_value
bpf: Do not try bpf_msg_push_data with len 0
====================
Link: https://lore.kernel.org/r/20220217190000.37925-1-alexei.starovoitov@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
syzbot reported various soft lockups caused by bpf batch operations.
INFO: task kworker/1:1:27 blocked for more than 140 seconds.
INFO: task hung in rcu_barrier
Nothing prevents batch ops to process huge amount of data,
we need to add schedule points in them.
Note that maybe_wait_bpf_programs(map) calls from
generic_map_delete_batch() can be factorized by moving
the call after the loop.
This will be done later in -next tree once we get this fix merged,
unless there is strong opinion doing this optimization sooner.
Fixes: aa2e93b8e5 ("bpf: Add generic support for update and delete batch ops")
Fixes: cb4d03ab49 ("bpf: Add generic support for lookup batch op")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Stanislav Fomichev <sdf@google.com>
Acked-by: Brian Vazquez <brianvv@google.com>
Link: https://lore.kernel.org/bpf/20220217181902.808742-1-eric.dumazet@gmail.com
While examining is_ucounts_overlimit and reading the various messages
I realized that is_ucounts_overlimit fails to deal with counts that
may have wrapped.
Being wrapped should be a transitory state for counts and they should
never be wrapped for long, but it can happen so handle it.
Cc: stable@vger.kernel.org
Fixes: 21d1c5e386 ("Reimplement RLIMIT_NPROC on top of ucounts")
Link: https://lkml.kernel.org/r/20220216155832.680775-5-ebiederm@xmission.com
Reviewed-by: Shuah Khan <skhan@linuxfoundation.org>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
During set*id() which cred->ucounts to charge the the current process
to is not known until after set_cred_ucounts. So move the
RLIMIT_NPROC checking into a new helper flag_nproc_exceeded and call
flag_nproc_exceeded after set_cred_ucounts.
This is very much an arbitrary subset of the places where we currently
change the RLIMIT_NPROC accounting, designed to preserve the existing
logic.
Fixing the existing logic will be the subject of another series of
changes.
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20220216155832.680775-4-ebiederm@xmission.com
Fixes: 21d1c5e386 ("Reimplement RLIMIT_NPROC on top of ucounts")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Michal Koutný <mkoutny@suse.com> wrote:
> Tasks are associated to multiple users at once. Historically and as per
> setrlimit(2) RLIMIT_NPROC is enforce based on real user ID.
>
> The commit 21d1c5e386 ("Reimplement RLIMIT_NPROC on top of ucounts")
> made the accounting structure "indexed" by euid and hence potentially
> account tasks differently.
>
> The effective user ID may be different e.g. for setuid programs but
> those are exec'd into already existing task (i.e. below limit), so
> different accounting is moot.
>
> Some special setresuid(2) users may notice the difference, justifying
> this fix.
I looked at cred->ucount and it is only used for rlimit operations
that were previously stored in cred->user. Making the fact
cred->ucount can refer to a different user from cred->user a bug,
affecting all uses of cred->ulimit not just RLIMIT_NPROC.
Fix set_cred_ucounts to always use the real uid not the effective uid.
Further simplify set_cred_ucounts by noticing that set_cred_ucounts
somehow retained a draft version of the check to see if alloc_ucounts
was needed that checks the new->user and new->user_ns against the
current_real_cred(). Remove that draft version of the check.
All that matters for setting the cred->ucounts are the user_ns and uid
fields in the cred.
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/20220207121800.5079-4-mkoutny@suse.com
Link: https://lkml.kernel.org/r/20220216155832.680775-3-ebiederm@xmission.com
Reported-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Fixes: 21d1c5e386 ("Reimplement RLIMIT_NPROC on top of ucounts")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Michal Koutný <mkoutny@suse.com> wrote:
> It was reported that v5.14 behaves differently when enforcing
> RLIMIT_NPROC limit, namely, it allows one more task than previously.
> This is consequence of the commit 21d1c5e386 ("Reimplement
> RLIMIT_NPROC on top of ucounts") that missed the sharpness of
> equality in the forking path.
This can be fixed either by fixing the test or by moving the increment
to be before the test. Fix it my moving copy_creds which contains
the increment before is_ucounts_overlimit.
In the case of CLONE_NEWUSER the ucounts in the task_cred changes.
The function is_ucounts_overlimit needs to use the final version of
the ucounts for the new process. Which means moving the
is_ucounts_overlimit test after copy_creds is necessary.
Both the test in fork and the test in set_user were semantically
changed when the code moved to ucounts. The change of the test in
fork was bad because it was before the increment. The test in
set_user was wrong and the change to ucounts fixed it. So this
fix only restores the old behavior in one lcation not two.
Link: https://lkml.kernel.org/r/20220204181144.24462-1-mkoutny@suse.com
Link: https://lkml.kernel.org/r/20220216155832.680775-2-ebiederm@xmission.com
Cc: stable@vger.kernel.org
Reported-by: Michal Koutný <mkoutny@suse.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Fixes: 21d1c5e386 ("Reimplement RLIMIT_NPROC on top of ucounts")
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Solar Designer <solar@openwall.com> wrote:
> I'm not aware of anyone actually running into this issue and reporting
> it. The systems that I personally know use suexec along with rlimits
> still run older/distro kernels, so would not yet be affected.
>
> So my mention was based on my understanding of how suexec works, and
> code review. Specifically, Apache httpd has the setting RLimitNPROC,
> which makes it set RLIMIT_NPROC:
>
> https://httpd.apache.org/docs/2.4/mod/core.html#rlimitnproc
>
> The above documentation for it includes:
>
> "This applies to processes forked from Apache httpd children servicing
> requests, not the Apache httpd children themselves. This includes CGI
> scripts and SSI exec commands, but not any processes forked from the
> Apache httpd parent, such as piped logs."
>
> In code, there are:
>
> ./modules/generators/mod_cgid.c: ( (cgid_req.limits.limit_nproc_set) && ((rc = apr_procattr_limit_set(procattr, APR_LIMIT_NPROC,
> ./modules/generators/mod_cgi.c: ((rc = apr_procattr_limit_set(procattr, APR_LIMIT_NPROC,
> ./modules/filters/mod_ext_filter.c: rv = apr_procattr_limit_set(procattr, APR_LIMIT_NPROC, conf->limit_nproc);
>
> For example, in mod_cgi.c this is in run_cgi_child().
>
> I think this means an httpd child sets RLIMIT_NPROC shortly before it
> execs suexec, which is a SUID root program. suexec then switches to the
> target user and execs the CGI script.
>
> Before 2863643fb8, the setuid() in suexec would set the flag, and the
> target user's process count would be checked against RLIMIT_NPROC on
> execve(). After 2863643fb8, the setuid() in suexec wouldn't set the
> flag because setuid() is (naturally) called when the process is still
> running as root (thus, has those limits bypass capabilities), and
> accordingly execve() would not check the target user's process count
> against RLIMIT_NPROC.
In commit 2863643fb8 ("set_user: add capability check when
rlimit(RLIMIT_NPROC) exceeds") capable calls were added to set_user to
make it more consistent with fork. Unfortunately because of call site
differences those capable calls were checking the credentials of the
user before set*id() instead of after set*id().
This breaks enforcement of RLIMIT_NPROC for applications that set the
rlimit and then call set*id() while holding a full set of
capabilities. The capabilities are only changed in the new credential
in security_task_fix_setuid().
The code in apache suexec appears to follow this pattern.
Commit 909cc4ae86f3 ("[PATCH] Fix two bugs with process limits
(RLIMIT_NPROC)") where this check was added describes the targes of this
capability check as:
2/ When a root-owned process (e.g. cgiwrap) sets up process limits and then
calls setuid, the setuid should fail if the user would then be running
more than rlim_cur[RLIMIT_NPROC] processes, but it doesn't. This patch
adds an appropriate test. With this patch, and per-user process limit
imposed in cgiwrap really works.
So the original use case of this check also appears to match the broken
pattern.
Restore the enforcement of RLIMIT_NPROC by removing the bad capable
checks added in set_user. This unfortunately restores the
inconsistent state the code has been in for the last 11 years, but
dealing with the inconsistencies looks like a larger problem.
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20210907213042.GA22626@openwall.com/
Link: https://lkml.kernel.org/r/20220212221412.GA29214@openwall.com
Link: https://lkml.kernel.org/r/20220216155832.680775-1-ebiederm@xmission.com
Fixes: 2863643fb8 ("set_user: add capability check when rlimit(RLIMIT_NPROC) exceeds")
History-Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Reviewed-by: Solar Designer <solar@openwall.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Sysfs support might be disabled so we need to guard the code that
instantiates "compression" attribute with an #ifdef.
Fixes: b1ae6dc41e ("module: add in-kernel support for decompressing")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
When commit e6ac2450d6 ("bpf: Support bpf program calling kernel function") added
kfunc support, it defined reg2btf_ids as a cheap way to translate the verifier
reg type to the appropriate btf_vmlinux BTF ID, however
commit c25b2ae136 ("bpf: Replace PTR_TO_XXX_OR_NULL with PTR_TO_XXX | PTR_MAYBE_NULL")
moved the __BPF_REG_TYPE_MAX from the last member of bpf_reg_type enum to after
the base register types, and defined other variants using type flag
composition. However, now, the direct usage of reg->type to index into
reg2btf_ids may no longer fall into __BPF_REG_TYPE_MAX range, and hence lead to
out of bounds access and kernel crash on dereference of bad pointer.
Fixes: c25b2ae136 ("bpf: Replace PTR_TO_XXX_OR_NULL with PTR_TO_XXX | PTR_MAYBE_NULL")
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20220216201943.624869-1-memxor@gmail.com
As previously discussed(https://lkml.org/lkml/2022/1/20/51),
cpuset_attach() is affected with similar cpu hotplug race,
as follow scenario:
cpuset_attach() cpu hotplug
--------------------------- ----------------------
down_write(cpuset_rwsem)
guarantee_online_cpus() // (load cpus_attach)
sched_cpu_deactivate
set_cpu_active()
// will change cpu_active_mask
set_cpus_allowed_ptr(cpus_attach)
__set_cpus_allowed_ptr_locked()
// (if the intersection of cpus_attach and
cpu_active_mask is empty, will return -EINVAL)
up_write(cpuset_rwsem)
To avoid races such as described above, protect cpuset_attach() call
with cpu_hotplug_lock.
Fixes: be367d0992 ("cgroups: let ss->can_attach and ss->attach do whole threadgroups at a time")
Cc: stable@vger.kernel.org # v2.6.32+
Reported-by: Zhao Gongyi <zhaogongyi@huawei.com>
Signed-off-by: Zhang Qiao <zhangqiao22@huawei.com>
Acked-by: Waiman Long <longman@redhat.com>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
The problem I'm addressing was discovered by the LTP test covering
cve-2018-1000204.
A short description of what happens follows:
1) The test case issues a command code 00 (TEST UNIT READY) via the SG_IO
interface with: dxfer_len == 524288, dxdfer_dir == SG_DXFER_FROM_DEV
and a corresponding dxferp. The peculiar thing about this is that TUR
is not reading from the device.
2) In sg_start_req() the invocation of blk_rq_map_user() effectively
bounces the user-space buffer. As if the device was to transfer into
it. Since commit a45b599ad8 ("scsi: sg: allocate with __GFP_ZERO in
sg_build_indirect()") we make sure this first bounce buffer is
allocated with GFP_ZERO.
3) For the rest of the story we keep ignoring that we have a TUR, so the
device won't touch the buffer we prepare as if the we had a
DMA_FROM_DEVICE type of situation. My setup uses a virtio-scsi device
and the buffer allocated by SG is mapped by the function
virtqueue_add_split() which uses DMA_FROM_DEVICE for the "in" sgs (here
scatter-gather and not scsi generics). This mapping involves bouncing
via the swiotlb (we need swiotlb to do virtio in protected guest like
s390 Secure Execution, or AMD SEV).
4) When the SCSI TUR is done, we first copy back the content of the second
(that is swiotlb) bounce buffer (which most likely contains some
previous IO data), to the first bounce buffer, which contains all
zeros. Then we copy back the content of the first bounce buffer to
the user-space buffer.
5) The test case detects that the buffer, which it zero-initialized,
ain't all zeros and fails.
One can argue that this is an swiotlb problem, because without swiotlb
we leak all zeros, and the swiotlb should be transparent in a sense that
it does not affect the outcome (if all other participants are well
behaved).
Copying the content of the original buffer into the swiotlb buffer is
the only way I can think of to make swiotlb transparent in such
scenarios. So let's do just that if in doubt, but allow the driver
to tell us that the whole mapped buffer is going to be overwritten,
in which case we can preserve the old behavior and avoid the performance
impact of the extra bounce.
Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
