diff options
| -rw-r--r-- | kernel/bpf/verifier.c | 39 |
1 files changed, 39 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 02a43cafbb25..9d3ad2876d8f 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -15491,6 +15491,35 @@ static bool is_safe_to_compute_dst_reg_range(struct bpf_insn *insn, } } +static int maybe_fork_scalars(struct bpf_verifier_env *env, struct bpf_insn *insn, + struct bpf_reg_state *dst_reg) +{ + struct bpf_verifier_state *branch; + struct bpf_reg_state *regs; + bool alu32; + + if (dst_reg->smin_value == -1 && dst_reg->smax_value == 0) + alu32 = false; + else if (dst_reg->s32_min_value == -1 && dst_reg->s32_max_value == 0) + alu32 = true; + else + return 0; + + branch = push_stack(env, env->insn_idx + 1, env->insn_idx, false); + if (IS_ERR(branch)) + return PTR_ERR(branch); + + regs = branch->frame[branch->curframe]->regs; + if (alu32) { + __mark_reg32_known(®s[insn->dst_reg], 0); + __mark_reg32_known(dst_reg, -1ull); + } else { + __mark_reg_known(®s[insn->dst_reg], 0); + __mark_reg_known(dst_reg, -1ull); + } + return 0; +} + /* WARNING: This function does calculations on 64-bit values, but the actual * execution may occur on 32-bit values. Therefore, things like bitshifts * need extra checks in the 32-bit case. @@ -15553,11 +15582,21 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, scalar_min_max_mul(dst_reg, &src_reg); break; case BPF_AND: + if (tnum_is_const(src_reg.var_off)) { + ret = maybe_fork_scalars(env, insn, dst_reg); + if (ret) + return ret; + } dst_reg->var_off = tnum_and(dst_reg->var_off, src_reg.var_off); scalar32_min_max_and(dst_reg, &src_reg); scalar_min_max_and(dst_reg, &src_reg); break; case BPF_OR: + if (tnum_is_const(src_reg.var_off)) { + ret = maybe_fork_scalars(env, insn, dst_reg); + if (ret) + return ret; + } dst_reg->var_off = tnum_or(dst_reg->var_off, src_reg.var_off); scalar32_min_max_or(dst_reg, &src_reg); scalar_min_max_or(dst_reg, &src_reg); |