[PATCH 4.5 006/101] bpf/verifier: reject invalid LD_ABS | BPF_DW instruction

Greg Kroah-Hartman
2016-05-17T01:26:26Z

From: Alexei Starovoitov <ast@fb.com>

[ Upstream commit d82bccc69041a51f7b7b9b4a36db0772f4cdba21 ]

verifier must check for reserved size bits in instruction opcode and
reject BPF_LD | BPF_ABS | BPF_DW and BPF_LD | BPF_IND | BPF_DW instructions,
otherwise interpreter will WARN_RATELIMIT on them during execution.

Fixes: ddd872bc3098 ("bpf: verifier: add checks for BPF_ABS | BPF_IND instructions")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
kernel/bpf/verifier.c | 1 +
1 file changed, 1 insertion(+)

--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1348,6 +1348,7 @@ static int check_ld_abs(struct verifier_
}

if (insn->dst_reg != BPF_REG_0 || insn->off != 0 ||
+ BPF_SIZE(insn->code) == BPF_DW ||
(mode == BPF_ABS && insn->src_reg != BPF_REG_0)) {
verbose("BPF_LD_ABS uses reserved fields\n");
return -EINVAL;