diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/tnum.c | 10 | ||||
| -rw-r--r-- | kernel/bpf/verifier.c | 23 |
2 files changed, 33 insertions, 0 deletions
diff --git a/kernel/bpf/tnum.c b/kernel/bpf/tnum.c index 1f4bf68c12db..938d41211be7 100644 --- a/kernel/bpf/tnum.c +++ b/kernel/bpf/tnum.c @@ -43,6 +43,16 @@ struct tnum tnum_rshift(struct tnum a, u8 shift) return TNUM(a.value >> shift, a.mask >> shift); } +struct tnum tnum_arshift(struct tnum a, u8 min_shift) +{ + /* if a.value is negative, arithmetic shifting by minimum shift + * will have larger negative offset compared to more shifting. + * If a.value is nonnegative, arithmetic shifting by minimum shift + * will have larger positive offset compare to more shifting. + */ + return TNUM((s64)a.value >> min_shift, (s64)a.mask >> min_shift); +} + struct tnum tnum_add(struct tnum a, struct tnum b) { u64 sm, sv, sigma, chi, mu; diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6e3f859b3abf..712d8655e916 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2974,6 +2974,29 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, /* We may learn something more from the var_off */ __update_reg_bounds(dst_reg); break; + case BPF_ARSH: + if (umax_val >= insn_bitness) { + /* Shifts greater than 31 or 63 are undefined. + * This includes shifts by a negative number. + */ + mark_reg_unknown(env, regs, insn->dst_reg); + break; + } + + /* Upon reaching here, src_known is true and + * umax_val is equal to umin_val. + */ + dst_reg->smin_value >>= umin_val; + dst_reg->smax_value >>= umin_val; + dst_reg->var_off = tnum_arshift(dst_reg->var_off, umin_val); + + /* blow away the dst_reg umin_value/umax_value and rely on + * dst_reg var_off to refine the result. + */ + dst_reg->umin_value = 0; + dst_reg->umax_value = U64_MAX; + __update_reg_bounds(dst_reg); + break; default: mark_reg_unknown(env, regs, insn->dst_reg); break; |