Commit 3ac1a467 authored by Junyoung Jang's avatar Junyoung Jang Committed by Alexei Starovoitov
Browse files

bpf: Fix off-by-one boundary validation in arena direct-value access 



BPF_MAP_TYPE_ARENA accepts BPF_PSEUDO_MAP_VALUE offsets at exactly
the end of the arena mapping (off == arena_size). The boundary check
in arena_map_direct_value_addr() uses `>` instead of `>=`, which
incorrectly allows a one-past-end pointer to be accepted.

Change the condition to `>=` to correctly reject offsets that fall
outside the valid arena user_vm range.

Fixes: 31746031 ("bpf: Introduce bpf_arena.")
Signed-off-by: default avatarJunyoung Jang <graypanda.inzag@gmail.com>
Reviewed-by: default avatarEmil Tsalapatis <emil@etsalapatis.com>
Link: https://lore.kernel.org/r/20260426172505.1947915-1-graypanda.inzag@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent bf6d507f

kernel/bpf/arena.c

+1 −1
Original line number Diff line number Diff line
@@ -511,7 +511,7 @@ static int arena_map_direct_value_addr(const struct bpf_map *map, u64 *imm, u32 
{

	struct bpf_arena *arena = container_of(map, struct bpf_arena, map);



	if ((u64)off > arena->user_vm_end - arena->user_vm_start)

	if ((u64)off >= arena->user_vm_end - arena->user_vm_start)

		return -ERANGE;

	*imm = (unsigned long)arena->user_vm_start;

	return 0;