diff options
| -rw-r--r-- | kernel/bpf/verifier.c | 21 |
1 files changed, 12 insertions, 9 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 1fbb0b51c429..a339a39d895c 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10791,16 +10791,19 @@ static void mark_ptr_or_null_reg(struct bpf_func_state *state, { if (type_may_be_null(reg->type) && reg->id == id && !WARN_ON_ONCE(!reg->id)) { - if (WARN_ON_ONCE(reg->smin_value || reg->smax_value || - !tnum_equals_const(reg->var_off, 0) || - reg->off)) { - /* Old offset (both fixed and variable parts) should - * have been known-zero, because we don't allow pointer - * arithmetic on pointers that might be NULL. If we - * see this happening, don't convert the register. - */ + /* Old offset (both fixed and variable parts) should have been + * known-zero, because we don't allow pointer arithmetic on + * pointers that might be NULL. If we see this happening, don't + * convert the register. + * + * But in some cases, some helpers that return local kptrs + * advance offset for the returned pointer. In those cases, it + * is fine to expect to see reg->off. + */ + if (WARN_ON_ONCE(reg->smin_value || reg->smax_value || !tnum_equals_const(reg->var_off, 0))) + return; + if (reg->type != (PTR_TO_BTF_ID | MEM_ALLOC | PTR_MAYBE_NULL) && WARN_ON_ONCE(reg->off)) return; - } if (is_null) { reg->type = SCALAR_VALUE; /* We don't need id and ref_obj_id from this point |