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bpf: Check percpu map value size first

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Percpu map is often used, but the map value size limit often ignored,
like issue: https://github.com/iovisor/bcc/issues/2519. Actually,
percpu map value size is bound by PCPU_MIN_UNIT_SIZE, so we
can check the value size whether it exceeds PCPU_MIN_UNIT_SIZE first,
like percpu map of local_storage. Maybe the error message seems clearer
compared with "cannot allocate memory".

Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Tao Chen <chen.dylane@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240910144111.1464912-2-chen.dylane@gmail.com
This commit is contained in:
Tao Chen 2024-09-10 22:41:10 +08:00 committed by Andrii Nakryiko
parent 300a90b2cb
commit 1d244784be
2 changed files with 6 additions and 0 deletions
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3
kernel/bpf/arraymap.c
View File

@ -73,6 +73,9 @@ int array_map_alloc_check(union bpf_attr *attr)
/* avoid overflow on round_up(map->value_size) */
if (attr->value_size > INT_MAX)
return -E2BIG;
/* percpu map value size is bound by PCPU_MIN_UNIT_SIZE */
if (percpu && round_up(attr->value_size, 8) > PCPU_MIN_UNIT_SIZE)
return -E2BIG;
return 0;
}

3
kernel/bpf/hashtab.c
View File

@ -462,6 +462,9 @@ static int htab_map_alloc_check(union bpf_attr *attr)
* kmalloc-able later in htab_map_update_elem()
*/
return -E2BIG;
/* percpu map value size is bound by PCPU_MIN_UNIT_SIZE */
if (percpu && round_up(attr->value_size, 8) > PCPU_MIN_UNIT_SIZE)
return -E2BIG;
return 0;
}