diff options
| author | Alexei Starovoitov <ast@kernel.org> | 2017-12-18 20:12:00 -0800 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2017-12-21 02:15:41 +0100 |
| commit | bb7f0f989ca7de1153bd128a40a71709e339fa03 (patch) | |
| tree | 1667911dc70762b44fac20651cd8e23b73c257cf /include/linux/bpf_verifier.h | |
| parent | 179d1c5602997fef5a940c6ddcf31212cbfebd14 (diff) | |
| download | lwn-bb7f0f989ca7de1153bd128a40a71709e339fa03.tar.gz lwn-bb7f0f989ca7de1153bd128a40a71709e339fa03.zip | |
bpf: fix integer overflows
There were various issues related to the limited size of integers used in
the verifier:
- `off + size` overflow in __check_map_access()
- `off + reg->off` overflow in check_mem_access()
- `off + reg->var_off.value` overflow or 32-bit truncation of
`reg->var_off.value` in check_mem_access()
- 32-bit truncation in check_stack_boundary()
Make sure that any integer math cannot overflow by not allowing
pointer math with large values.
Also reduce the scope of "scalar op scalar" tracking.
Fixes: f1174f77b50c ("bpf/verifier: rework value tracking")
Reported-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 'include/linux/bpf_verifier.h')
| -rw-r--r-- | include/linux/bpf_verifier.h | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h index c561b986bab0..1632bb13ad8a 100644 --- a/include/linux/bpf_verifier.h +++ b/include/linux/bpf_verifier.h @@ -15,11 +15,11 @@ * In practice this is far bigger than any realistic pointer offset; this limit * ensures that umax_value + (int)off + (int)size cannot overflow a u64. */ -#define BPF_MAX_VAR_OFF (1ULL << 31) +#define BPF_MAX_VAR_OFF (1 << 29) /* Maximum variable size permitted for ARG_CONST_SIZE[_OR_ZERO]. This ensures * that converting umax_value to int cannot overflow. */ -#define BPF_MAX_VAR_SIZ INT_MAX +#define BPF_MAX_VAR_SIZ (1 << 29) /* Liveness marks, used for registers and spilled-regs (in stack slots). * Read marks propagate upwards until they find a write mark; they record that |