linux/mm
Jiri Kosina c1d171a002 x86: randomize brk
Randomize the location of the heap (brk) for i386 and x86_64.  The range is
randomized in the range starting at current brk location up to 0x02000000
offset for both architectures.  This, together with
pie-executable-randomization.patch and
pie-executable-randomization-fix.patch, should make the address space
randomization on i386 and x86_64 complete.

Arjan says:

This is known to break older versions of some emacs variants, whose dumper
code assumed that the last variable declared in the program is equal to the
start of the dynamically allocated memory region.

(The dumper is the code where emacs effectively dumps core at the end of it's
compilation stage; this coredump is then loaded as the main program during
normal use)

iirc this was 5 years or so; we found this way back when I was at RH and we
first did the security stuff there (including this brk randomization).  It
wasn't all variants of emacs, and it got fixed as a result (I vaguely remember
that emacs already had code to deal with it for other archs/oses, just
ifdeffed wrongly).

It's a rare and wrong assumption as a general thing, just on x86 it mostly
happened to be true (but to be honest, it'll break too if gcc does
something fancy or if the linker does a non-standard order).  Still its
something we should at least document.

Note 2: afaik it only broke the emacs *build*.  I'm not 100% sure about that
(it IS 5 years ago) though.

[ akpm@linux-foundation.org: deuglification ]

Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Roland McGrath <roland@redhat.com>
Cc: Jakub Jelinek <jakub@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-01-30 13:30:40 +01:00
..
allocpercpu.c Slab allocators: Replace explicit zeroing with __GFP_ZERO 2007-07-17 10:23:02 -07:00
backing-dev.c mm/backing-dev.c: fix percpu_counter_destroy call bug in bdi_init 2007-12-05 09:21:18 -08:00
bootmem.c [PATCH] remove EXPORT_UNUSED_SYMBOL'ed symbols 2006-12-07 08:39:44 -08:00
bounce.c block: Initial support for data-less (or empty) barrier support 2007-10-16 11:03:56 +02:00
fadvise.c [PATCH] mm: change uses of f_{dentry,vfsmnt} to use f_path 2006-12-08 08:28:43 -08:00
filemap.c Do dirty page accounting when removing a page from the page cache 2007-12-19 14:05:13 -08:00
filemap_xip.c xip: fix get_zeroed_page with __GFP_HIGHMEM 2008-01-08 16:10:36 -08:00
fremap.c remap_file_pages: kernel-doc corrections 2007-10-17 08:43:07 -07:00
highmem.c Create the ZONE_MOVABLE zone 2007-07-17 10:22:59 -07:00
hugetlb.c fix hugepages leak due to pagetable page sharing 2008-01-24 08:07:27 -08:00
internal.h Breakout page_order() to internal.h to avoid special knowledge of the buddy allocator 2007-10-16 09:43:01 -07:00
Kconfig sh: Bump number of quicklists for SH-5. 2008-01-28 13:18:55 +09:00
madvise.c speed up madvise_need_mmap_write() usage 2007-07-16 09:05:36 -07:00
Makefile memory unplug: page isolation 2007-10-16 09:43:02 -07:00
memory.c Update ctime and mtime for memory-mapped files 2008-01-23 09:58:55 -08:00
memory_hotplug.c Add IORESOUCE_BUSY flag for System RAM 2007-11-14 18:45:39 -08:00
mempolicy.c Migration: find correct vma in new_vma_page() 2007-11-14 18:45:38 -08:00
mempool.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
migrate.c Typo fixes retrun -> return 2007-10-20 02:13:26 +02:00
mincore.c [PATCH] mincore: vma crossing fix 2007-02-15 09:57:03 -08:00
mlock.c do not limit locked memory when RLIMIT_MEMLOCK is RLIM_INFINITY 2007-07-16 09:05:37 -07:00
mmap.c x86: randomize brk 2008-01-30 13:30:40 +01:00
mmzone.c [PATCH] remove EXPORT_UNUSED_SYMBOL'ed symbols 2006-12-07 08:39:44 -08:00
mprotect.c fix mprotect vma_wants_writenotify prot 2007-10-23 08:32:06 -07:00
mremap.c sparse pointer use of zero as null 2007-10-18 14:37:31 -07:00
msync.c Detach sched.h from mm.h 2007-05-21 09:18:19 -07:00
nommu.c Security: round mmap hint address above mmap_min_addr 2007-12-06 00:25:10 +11:00
oom_kill.c sched: sched_rt_entity 2008-01-25 21:08:27 +01:00
page-writeback.c Revert "writeback: introduce writeback_control.more_io to indicate more io" 2008-01-14 21:21:29 -08:00
page_alloc.c mm: fix section mismatch warning in page_alloc.c 2008-01-17 15:38:58 -08:00
page_io.c Drop 'size' argument from bio_endio and bi_end_io 2007-10-10 09:25:57 +02:00
page_isolation.c memory hotremove: unset migrate type "ISOLATE" after removal 2007-11-14 18:45:38 -08:00
pdflush.c Freezer: make kernel threads nonfreezable by default 2007-07-17 10:23:02 -07:00
prio_tree.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
quicklist.c quicklists: Only consider memory that can be used with GFP_KERNEL 2008-01-14 08:52:22 -08:00
readahead.c mm: bdi init hooks 2007-10-17 08:42:45 -07:00
rmap.c [S390] Optimize storage key handling for anonymous pages 2007-11-20 11:13:46 +01:00
shmem.c tmpfs: restore missing clear_highpage 2007-11-28 11:04:28 -08:00
shmem_acl.c [PATCH] Fix typos in mm/shmem_acl.c 2006-10-11 11:14:23 -07:00
slab.c cpu-hotplug: replace per-subsystem mutexes with get_online_cpus() 2008-01-25 21:08:02 +01:00
slob.c Avoid double memclear() in SLOB/SLUB 2007-12-09 10:17:52 -08:00
slub.c Kobject: convert mm/slub.c to use kobject_init/add_ng() 2008-01-24 20:40:31 -08:00
sparse-vmemmap.c memory hotplug fix: fix section mismatch in vmammap_allock_block() 2007-11-29 09:24:54 -08:00
sparse.c mm/sparse.c: improve the error handling for sparse_add_one_section() 2007-12-17 19:28:16 -08:00
swap.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
swap_state.c mm: clarify __add_to_swap_cache locking 2007-10-16 09:42:53 -07:00
swapfile.c Replace CONFIG_SOFTWARE_SUSPEND with CONFIG_HIBERNATION 2007-07-29 16:45:38 -07:00
thrash.c Bug in mm/thrash.c function grab_swap_token() 2007-05-11 08:29:32 -07:00
tiny-shmem.c r/o bind mounts: filesystem helpers for custom 'struct file's 2007-10-17 08:43:04 -07:00
truncate.c Drop some headers from mm.h 2007-10-17 08:42:55 -07:00
util.c fix mm/util.c:krealloc() 2007-11-14 18:45:41 -08:00
vmalloc.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
vmscan.c spelling fixes: mm/ 2007-10-20 01:27:18 +02:00
vmstat.c vmstat: fix section mismatch warning 2007-11-14 18:45:42 -08:00