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| author | Alexei Starovoitov <ast@fb.com> | 2018-01-08 18:51:17 +0300 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2018-01-08 20:19:03 +0300 |
| commit | 5896351ea9360072f8bdd9eee186861a9d13db6d (patch) | |
| tree | a5f33a910ae80287db97600e8631b0425d4c204a /kernel/bpf | |
| parent | f66faae2f80a45feafc04ce63ef744ac4b6e8c05 (diff) | |
| download | linux-5896351ea9360072f8bdd9eee186861a9d13db6d.tar.xz | |
bpf: fix verifier GPF in kmalloc failure path
syzbot reported the following panic in the verifier triggered
by kmalloc error injection:
kasan: GPF could be caused by NULL-ptr deref or user memory access
RIP: 0010:copy_func_state kernel/bpf/verifier.c:403 [inline]
RIP: 0010:copy_verifier_state+0x364/0x590 kernel/bpf/verifier.c:431
Call Trace:
pop_stack+0x8c/0x270 kernel/bpf/verifier.c:449
push_stack kernel/bpf/verifier.c:491 [inline]
check_cond_jmp_op kernel/bpf/verifier.c:3598 [inline]
do_check+0x4b60/0xa050 kernel/bpf/verifier.c:4731
bpf_check+0x3296/0x58c0 kernel/bpf/verifier.c:5489
bpf_prog_load+0xa2a/0x1b00 kernel/bpf/syscall.c:1198
SYSC_bpf kernel/bpf/syscall.c:1807 [inline]
SyS_bpf+0x1044/0x4420 kernel/bpf/syscall.c:1769
when copy_verifier_state() aborts in the middle due to kmalloc failure
some of the frames could have been partially copied while
current free_verifier_state() loop
for (i = 0; i <= state->curframe; i++)
assumed that all frames are non-null.
Simply fix it by adding 'if (!state)' to free_func_state().
Also avoid stressing copy frame logic more if kzalloc fails
in push_stack() free env->cur_state right away.
Fixes: f4d7e40a5b71 ("bpf: introduce function calls (verification)")
Reported-by: syzbot+32ac5a3e473f2e01cfc7@syzkaller.appspotmail.com
Reported-by: syzbot+fa99e24f3c29d269a7d5@syzkaller.appspotmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/verifier.c | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index a2b211262c25..d921ab387b0b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -375,6 +375,8 @@ static int realloc_func_state(struct bpf_func_state *state, int size, static void free_func_state(struct bpf_func_state *state) { + if (!state) + return; kfree(state->stack); kfree(state); } @@ -487,6 +489,8 @@ static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env, } return &elem->st; err: + free_verifier_state(env->cur_state, true); + env->cur_state = NULL; /* pop all elements and return */ while (!pop_stack(env, NULL, NULL)); return NULL; |