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bpf: Fix ringbuf helper function compatibility

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Commit 457f44363a ("bpf: Implement BPF ring buffer and verifier support
for it") extended check_map_func_compatibility() by enforcing map -> helper
function match, but not helper -> map type match.

Due to this all of the bpf_ringbuf_*() helper functions could be used with
a wrong map type such as array or hash map, leading to invalid access due
to type confusion.

Also, both BPF_FUNC_ringbuf_{submit,discard} have ARG_PTR_TO_ALLOC_MEM as
argument and not a BPF map. Therefore, their check_map_func_compatibility()
presence is incorrect since it's only for map type checking.

Fixes: 457f44363a ("bpf: Implement BPF ring buffer and verifier support for it")
Reported-by: Ryota Shiga (Flatt Security)
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Daniel Borkmann 2021-08-23 21:02:09 +02:00
parent 82a44ae113
commit 5b029a32cf
1 changed files with 6 additions and 2 deletions
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8
kernel/bpf/verifier.c
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@ -5150,8 +5150,6 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
case BPF_MAP_TYPE_RINGBUF:
if (func_id != BPF_FUNC_ringbuf_output &&
func_id != BPF_FUNC_ringbuf_reserve &&
func_id != BPF_FUNC_ringbuf_submit &&
func_id != BPF_FUNC_ringbuf_discard &&
func_id != BPF_FUNC_ringbuf_query)
goto error;
break;
@ -5260,6 +5258,12 @@ static int check_map_func_compatibility(struct bpf_verifier_env *env,
if (map->map_type != BPF_MAP_TYPE_PERF_EVENT_ARRAY)
goto error;
break;
case BPF_FUNC_ringbuf_output:
case BPF_FUNC_ringbuf_reserve:
case BPF_FUNC_ringbuf_query:
if (map->map_type != BPF_MAP_TYPE_RINGBUF)
goto error;
break;
case BPF_FUNC_get_stackid:
if (map->map_type != BPF_MAP_TYPE_STACK_TRACE)
goto error;