diff options
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 18 |
1 files changed, 7 insertions, 11 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index bb7eca1025c3..a31c032b2dd6 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -15300,21 +15300,17 @@ static void __scalar64_min_max_lsh(struct bpf_reg_state *dst_reg, u64 umin_val, u64 umax_val) { /* Special case <<32 because it is a common compiler pattern to sign - * extend subreg by doing <<32 s>>32. In this case if 32bit bounds are - * positive we know this shift will also be positive so we can track - * bounds correctly. Otherwise we lose all sign bit information except - * what we can pick up from var_off. Perhaps we can generalize this - * later to shifts of any length. + * extend subreg by doing <<32 s>>32. smin/smax assignments are correct + * because s32 bounds don't flip sign when shifting to the left by + * 32bits. */ - if (umin_val == 32 && umax_val == 32 && dst_reg->s32_max_value >= 0) + if (umin_val == 32 && umax_val == 32) { dst_reg->smax_value = (s64)dst_reg->s32_max_value << 32; - else - dst_reg->smax_value = S64_MAX; - - if (umin_val == 32 && umax_val == 32 && dst_reg->s32_min_value >= 0) dst_reg->smin_value = (s64)dst_reg->s32_min_value << 32; - else + } else { + dst_reg->smax_value = S64_MAX; dst_reg->smin_value = S64_MIN; + } /* If we might shift our top bit out, then we know nothing */ if (dst_reg->umax_value > 1ULL << (63 - umax_val)) { |