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| author | Daniel Borkmann <daniel@iogearbox.net> | 2021-03-23 11:04:10 +0300 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2021-04-17 00:51:43 +0300 |
| commit | b658bbb844e28f1862867f37e8ca11a8e2aa94a3 (patch) | |
| tree | b342f07b0438c09019ccd2f5fac52808a9a7d81e /kernel | |
| parent | 24c109bb1537c12c02aeed2d51a347b4d6a9b76e (diff) | |
| download | linux-b658bbb844e28f1862867f37e8ca11a8e2aa94a3.tar.xz | |
bpf: Rework ptr_limit into alu_limit and add common error path
Small refactor with no semantic changes in order to consolidate the max
ptr_limit boundary check.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index a21d7f1a0ba8..b8e0171d9591 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -5858,12 +5858,12 @@ static struct bpf_insn_aux_data *cur_aux(struct bpf_verifier_env *env) static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, const struct bpf_reg_state *off_reg, - u32 *ptr_limit, u8 opcode) + u32 *alu_limit, u8 opcode) { bool off_is_neg = off_reg->smin_value < 0; bool mask_to_left = (opcode == BPF_ADD && off_is_neg) || (opcode == BPF_SUB && !off_is_neg); - u32 off, max; + u32 off, max = 0, ptr_limit = 0; if (!tnum_is_const(off_reg->var_off) && (off_reg->smin_value < 0) != (off_reg->smax_value < 0)) @@ -5880,22 +5880,27 @@ static int retrieve_ptr_limit(const struct bpf_reg_state *ptr_reg, */ off = ptr_reg->off + ptr_reg->var_off.value; if (mask_to_left) - *ptr_limit = MAX_BPF_STACK + off; + ptr_limit = MAX_BPF_STACK + off; else - *ptr_limit = -off - 1; - return *ptr_limit >= max ? -ERANGE : 0; + ptr_limit = -off - 1; + break; case PTR_TO_MAP_VALUE: max = ptr_reg->map_ptr->value_size; if (mask_to_left) { - *ptr_limit = ptr_reg->umax_value + ptr_reg->off; + ptr_limit = ptr_reg->umax_value + ptr_reg->off; } else { off = ptr_reg->smin_value + ptr_reg->off; - *ptr_limit = ptr_reg->map_ptr->value_size - off - 1; + ptr_limit = ptr_reg->map_ptr->value_size - off - 1; } - return *ptr_limit >= max ? -ERANGE : 0; + break; default: return -EINVAL; } + + if (ptr_limit >= max) + return -ERANGE; + *alu_limit = ptr_limit; + return 0; } static bool can_skip_alu_sanitation(const struct bpf_verifier_env *env, |