diff options
| author | Jann Horn <jannh@google.com> | 2017-12-19 05:11:58 +0100 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2017-12-21 02:15:41 +0100 |
| commit | a5ec6ae161d72f01411169a938fa5f8baea16e8f (patch) | |
| tree | ac35208d260c569dff7eb526c5db93536e07b0f5 /kernel | |
| parent | bpf: fix missing error return in check_stack_boundary() (diff) | |
| download | linux-a5ec6ae161d72f01411169a938fa5f8baea16e8f.tar.xz linux-a5ec6ae161d72f01411169a938fa5f8baea16e8f.zip | |
bpf: force strict alignment checks for stack pointers
Force strict alignment checks for stack pointers because the tracking of
stack spills relies on it; unaligned stack accesses can lead to corruption
of spilled registers, which is exploitable.
Fixes: f1174f77b50c ("bpf/verifier: rework value tracking")
Signed-off-by: Jann Horn <jannh@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 77e4b5223867..102c519836f6 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1059,6 +1059,11 @@ static int check_ptr_alignment(struct bpf_verifier_env *env, break; case PTR_TO_STACK: pointer_desc = "stack "; + /* The stack spill tracking logic in check_stack_write() + * and check_stack_read() relies on stack accesses being + * aligned. + */ + strict = true; break; default: break; |