diff options
| author |   Daniel Borkmann <daniel@iogearbox.net> | 2022-01-05 11:35:13 -0800 |
|---|---|---|
| committer |   Alexei Starovoitov <ast@kernel.org> | 2022-01-05 12:00:19 -0800 |
| commit | e60b0d12a95dcf16a63225cead4541567f5cb517 (patch) | |
| tree | b5f8436c56edd7b551079b06936efb2de2b27f96 /kernel | |
| parent | bpf, sockmap: Fix double bpf_prog_put on error case in map_link (diff) | |
| download | linux-dev-e60b0d12a95dcf16a63225cead4541567f5cb517.tar.xz linux-dev-e60b0d12a95dcf16a63225cead4541567f5cb517.zip | |
bpf: Don't promote bogus looking registers after null check.
If we ever get to a point again where we convert a bogus looking <ptr>_or_null
typed register containing a non-zero fixed or variable offset, then lets not
reset these bounds to zero since they are not and also don't promote the register
to a <ptr> type, but instead leave it as <ptr>_or_null. Converting to a unknown
register could be an avenue as well, but then if we run into this case it would
allow to leak a kernel pointer this way.
Fixes: f1174f77b50c ("bpf/verifier: rework value tracking")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 12 |
1 files changed, 6 insertions, 6 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index b70c66c6db3b..c8d9e761173b 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -9079,15 +9079,15 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state, { if (type_may_be_null(reg->type) && reg->id == id && !WARN_ON_ONCE(!reg->id)) { - /* Old offset (both fixed and variable parts) should - * have been known-zero, because we don't allow pointer - * arithmetic on pointers that might be NULL. - */ if (WARN_ON_ONCE(reg->smin_value || reg->smax_value || !tnum_equals_const(reg->var_off, 0) || reg->off)) { - __mark_reg_known_zero(reg); - reg->off = 0; + /* Old offset (both fixed and variable parts) should + * have been known-zero, because we don't allow pointer + * arithmetic on pointers that might be NULL. If we + * see this happening, don't convert the register. + */ + return; } if (is_null) { reg->type = SCALAR_VALUE; |