bpf: Check percpu map value size first

[ Upstream commit 1d244784be6b01162b732a5a7d637dfc024c3203 ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index c76870bfd816772bf0d1062182c919842ff7def5..2788da290c21619db814a0be6204015c9590bceb 100644 (file)
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -74,6 +74,9 @@ int array_map_alloc_check(union bpf_attr *attr)
                 * access the elements.
                 */
                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;
 }

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index f53b4f04b935c5506ec296de5de665d250ce0a04..d08fe64e0e453ac13effb34b0dd3e7fb5d169397 100644 (file)
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -464,6 +464,9 @@ 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;
 }