diff options
| author | Zhiling Zou <zhilinz@nebusec.ai> | 2026-09-11 00:18:24 +0800 |
|---|---|---|
| committer | Eduard Zingerman <eddyz87@gmail.com> | 2026-09-17 10:56:16 -0700 |
| commit | 70504de0bb627848667207bec7ccfd647deb8814 (patch) | |
| tree | 975aab35c0c78b1fbc32b68c7f67bdc92c56cd2f /net/xdp | |
| parent | 9e4188d7a411103b6b1406dd67d55c3bbb637551 (diff) | |
xsk: Use a 32-bit compare in xsk_map_gen_lookup
xsk_map_gen_lookup() loads a u32 key and compares it with max_entries
using BPF_JMP_IMM. BPF immediates are sign-extended to 64 bits, so a
max_entries value of 0x80000000 or higher becomes a threshold larger
than every zero-extended 32-bit key. An out-of-range index then skips
the bounds check and the generated lookup reads past xsk_map[].
Compare with BPF_JMP32_IMM so the check stays in 32-bit unsigned range.
Fixes: e65650f291ee ("bpf: Implement map_gen_lookup() callback for XSKMAP")
Reported-by: Vega <vega@nebusec.ai>
Signed-off-by: Zhiling Zou <zhilinz@nebusec.ai>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Emil Tsalapatis <emil@etsalapatis.com>
Link: https://patch.msgid.link/7d2cb8e8dfaa9eb8fdff85156987a60960787dc3.1789056660.git.zhilinz@nebusec.ai
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Diffstat (limited to 'net/xdp')
| -rw-r--r-- | net/xdp/xskmap.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/net/xdp/xskmap.c b/net/xdp/xskmap.c index 3bff346308d0..bf00d6463c19 100644 --- a/net/xdp/xskmap.c +++ b/net/xdp/xskmap.c @@ -124,7 +124,7 @@ static int xsk_map_gen_lookup(struct bpf_map *map, struct bpf_insn *insn_buf) struct bpf_insn *insn = insn_buf; *insn++ = BPF_LDX_MEM(BPF_W, ret, index, 0); - *insn++ = BPF_JMP_IMM(BPF_JGE, ret, map->max_entries, 5); + *insn++ = BPF_JMP32_IMM(BPF_JGE, ret, map->max_entries, 5); *insn++ = BPF_ALU64_IMM(BPF_LSH, ret, ilog2(sizeof(struct xsk_sock *))); *insn++ = BPF_ALU64_IMM(BPF_ADD, mp, offsetof(struct xsk_map, xsk_map)); *insn++ = BPF_ALU64_REG(BPF_ADD, ret, mp); |