diff options
| author | Josef Bacik | 2016-11-29 12:27:09 -0500 |
|---|---|---|
| committer | David S. Miller | 2016-11-30 14:50:52 -0500 |
| commit | e2d2afe15ed452f91797a80dbc0a17838ba03ed4 (patch) | |
| tree | 44cb85851f4f9aebe00a6405197e4766bed2cf83 | |
| parent | 0fcba2894c6b370ebf4b49099d20ff6333a430f7 (diff) | |
bpf: fix states equal logic for varlen access
If we have a branch that looks something like this
int foo = map->value;
if (condition) {
foo += blah;
} else {
foo = bar;
}
map->array[foo] = baz;
We will incorrectly assume that the !condition branch is equal to the condition
branch as the register for foo will be UNKNOWN_VALUE in both cases. We need to
adjust this logic to only do this if we didn't do a varlen access after we
processed the !condition branch, otherwise we have different ranges and need to
check the other branch as well.
Fixes: 484611357c19 ("bpf: allow access into map value arrays")
Reported-by: Jann Horn <jannh@google.com>
Signed-off-by: Josef Bacik <jbacik@fb.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | kernel/bpf/verifier.c | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 6a936159c6e0..8199821f54cf 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2454,6 +2454,7 @@ static bool states_equal(struct bpf_verifier_env *env, struct bpf_verifier_state *old, struct bpf_verifier_state *cur) { + bool varlen_map_access = env->varlen_map_value_access; struct bpf_reg_state *rold, *rcur; int i; @@ -2467,12 +2468,17 @@ static bool states_equal(struct bpf_verifier_env *env, /* If the ranges were not the same, but everything else was and * we didn't do a variable access into a map then we are a-ok. */ - if (!env->varlen_map_value_access && + if (!varlen_map_access && rold->type == rcur->type && rold->imm == rcur->imm) continue; + /* If we didn't map access then again we don't care about the + * mismatched range values and it's ok if our old type was + * UNKNOWN and we didn't go to a NOT_INIT'ed reg. + */ if (rold->type == NOT_INIT || - (rold->type == UNKNOWN_VALUE && rcur->type != NOT_INIT)) + (!varlen_map_access && rold->type == UNKNOWN_VALUE && + rcur->type != NOT_INIT)) continue; if (rold->type == PTR_TO_PACKET && rcur->type == PTR_TO_PACKET && |