linux/kernel/bpf
Alexei Starovoitov 4f81c16f50 bpf: Recognize that two registers are safe when their ranges match
When open code iterators, bpf_loop or may_goto are used the following two
states are equivalent and safe to prune the search:

cur state: fp-8_w=scalar(id=3,smin=umin=smin32=umin32=2,smax=umax=smax32=umax32=11,var_off=(0x0; 0xf))
old state: fp-8_rw=scalar(id=2,smin=umin=smin32=umin32=1,smax=umax=smax32=umax32=11,var_off=(0x0; 0xf))

In other words "exact" state match should ignore liveness and precision
marks, since open coded iterator logic didn't complete their propagation,
reg_old->type == NOT_INIT && reg_cur->type != NOT_INIT is also not safe to
prune while looping, but range_within logic that applies to scalars,
ptr_to_mem, map_value, pkt_ptr is safe to rely on.

Avoid doing such comparison when regular infinite loop detection logic is
used, otherwise bounded loop logic will declare such "infinite loop" as
false positive. Such example is in progs/verifier_loops1.c
not_an_inifinite_loop().

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Tested-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20240306031929.42666-3-alexei.starovoitov@gmail.com
2024-03-06 15:18:00 -08:00
..
preload bpf: make preloaded map iterators to display map elements count 2023-07-06 12:42:25 -07:00
arraymap.c bpf: Consistently use BPF token throughout BPF verifier logic 2024-01-24 16:21:01 -08:00
bloom_filter.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
bpf_cgrp_storage.c bpf: Enable bpf_cgrp_storage for cgroup1 non-attach case 2023-12-08 17:08:18 -08:00
bpf_inode_storage.c
bpf_iter.c bpf: Add __bpf_kfunc_{start,end}_defs macros 2023-11-01 22:33:53 -07:00
bpf_local_storage.c bpf: Allow compiler to inline most of bpf_local_storage_lookup() 2024-02-11 14:06:24 -08:00
bpf_lru_list.c
bpf_lru_list.h bpf: lru: Remove unused declaration bpf_lru_promote() 2023-08-08 17:21:42 -07:00
bpf_lsm.c bpf: Minor clean-up to sleepable_lsm_hooks BTF set 2024-02-01 18:37:45 +01:00
bpf_struct_ops.c bpf: struct_ops supports more than one page for trampolines. 2024-03-04 14:09:20 -08:00
bpf_task_storage.c
btf.c bpf: don't infer PTR_TO_CTX for programs with unnamed context type 2024-02-13 18:46:47 -08:00
cgroup.c bpf: remove check in __cgroup_bpf_run_filter_skb 2024-02-13 15:41:17 -08:00
cgroup_iter.c bpf: Let verifier consider {task,cgroup} is trusted in bpf_iter_reg 2023-11-07 15:24:25 -08:00
core.c bpf: Introduce may_goto instruction 2024-03-06 15:17:31 -08:00
cpumap.c net, bpf: Add a warning if NAPI cb missed xdp_do_flush(). 2023-10-17 15:02:03 +02:00
cpumask.c bpf: treewide: Annotate BPF kfuncs in BTF 2024-01-31 20:40:56 -08:00
devmap.c net, bpf: Add a warning if NAPI cb missed xdp_do_flush(). 2023-10-17 15:02:03 +02:00
disasm.c bpf: Introduce may_goto instruction 2024-03-06 15:17:31 -08:00
disasm.h
dispatcher.c bpf: Use arch_bpf_trampoline_size 2023-12-06 17:17:20 -08:00
hashtab.c Networking changes for 6.8. 2024-01-11 10:07:29 -08:00
helpers.c bpf-next-for-netdev 2024-03-02 20:50:59 -08:00
inode.c bpf: Support symbolic BPF FS delegation mount options 2024-01-24 16:21:02 -08:00
Kconfig bpf: Merge two CONFIG_BPF entries 2024-02-07 16:38:20 -08:00
link_iter.c
local_storage.c
log.c bpf: improve duplicate source code line detection 2024-02-15 13:00:48 -08:00
lpm_trie.c bpf: Replace bpf_lpm_trie_key 0-length array with flexible array 2024-02-29 22:52:43 +01:00
Makefile bpf: Introduce BPF token object 2024-01-24 16:21:01 -08:00
map_in_map.c bpf: Optimize the free of inner map 2023-12-04 17:50:26 -08:00
map_in_map.h bpf: Add map and need_defer parameters to .map_fd_put_ptr() 2023-12-04 17:50:26 -08:00
map_iter.c bpf: treewide: Annotate BPF kfuncs in BTF 2024-01-31 20:40:56 -08:00
memalloc.c bpf: Remove unnecessary cpu == 0 check in memalloc 2024-01-04 10:18:14 -08:00
mmap_unlock_work.h
mprog.c bpf: Handle bpf_mprog_query with NULL entry 2023-10-06 17:11:20 -07:00
net_namespace.c
offload.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2023-09-21 21:49:45 +02:00
percpu_freelist.c
percpu_freelist.h
prog_iter.c
queue_stack_maps.c bpf: Avoid deadlock when using queue and stack maps from NMI 2023-09-11 19:04:49 -07:00
reuseport_array.c bpf: Centralize permissions checks for all BPF map types 2023-06-19 14:04:04 +02:00
ringbuf.c bpf: Fold smp_mb__before_atomic() into atomic_set_release() 2023-10-24 14:26:07 +02:00
stackmap.c bpf: Add crosstask check to __bpf_get_stack 2023-11-10 11:06:10 -08:00
syscall.c bpf,lsm: Refactor bpf_map_alloc/bpf_map_free LSM hooks 2024-01-24 16:21:01 -08:00
sysfs_btf.c
task_iter.c bpf: Fix an issue due to uninitialized bpf_iter_task 2024-02-19 12:28:15 +01:00
tcx.c bpf, tcx: Get rid of tcx_link_const 2023-10-23 15:01:53 -07:00
tnum.c bpf: simplify tnum output if a fully known constant 2023-12-02 11:36:51 -08:00
token.c bpf,token: Use BIT_ULL() to convert the bit mask 2024-01-29 20:04:55 -08:00
trampoline.c bpf: Use arch_bpf_trampoline_size 2023-12-06 17:17:20 -08:00
verifier.c bpf: Recognize that two registers are safe when their ranges match 2024-03-06 15:18:00 -08:00