diff options
Diffstat (limited to 'kernel/bpf')
| -rw-r--r-- | kernel/bpf/verifier.c | 31 |
1 files changed, 15 insertions, 16 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index e419e6024251..218a7ace4210 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -13074,6 +13074,21 @@ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold, return true; if (rcur->type == NOT_INIT) return false; + + /* Register types that are *not* MAYBE_NULL could technically be safe + * to use as their MAYBE_NULL variants (e.g., PTR_TO_MAP_VALUE is + * safe to be used as PTR_TO_MAP_VALUE_OR_NULL, provided both point to + * the same map). + * However, if the old MAYBE_NULL register then got NULL checked, + * doing so could have affected others with the same id, and we can't + * check for that because we lost the id when we converted to + * a non-MAYBE_NULL variant. + * So, as a general rule we don't allow mixing MAYBE_NULL and + * non-MAYBE_NULL registers. + */ + if (type_may_be_null(rold->type) != type_may_be_null(rcur->type)) + return false; + switch (base_type(rold->type)) { case SCALAR_VALUE: if (equal) @@ -13098,22 +13113,6 @@ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold, } case PTR_TO_MAP_KEY: case PTR_TO_MAP_VALUE: - /* a PTR_TO_MAP_VALUE could be safe to use as a - * PTR_TO_MAP_VALUE_OR_NULL into the same map. - * However, if the old PTR_TO_MAP_VALUE_OR_NULL then got NULL- - * checked, doing so could have affected others with the same - * id, and we can't check for that because we lost the id when - * we converted to a PTR_TO_MAP_VALUE. - */ - if (type_may_be_null(rold->type)) { - if (!type_may_be_null(rcur->type)) - return false; - if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, var_off))) - return false; - /* Check our ids match any regs they're supposed to */ - return check_ids(rold->id, rcur->id, idmap); - } - /* If the new min/max/var_off satisfy the old ones and * everything else matches, we are OK. */ |