bpf/verifier: reject invalid LD_ABS | BPF_DW instruction

[ 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>

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 2e7f7ab739e41c46072a69e787bf4e44f560ae55..c21cb146086c5f89dc7a7ce7b40504bea73178b5 100644 (file)
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1348,6 +1348,7 @@ static int check_ld_abs(struct verifier_env *env, struct bpf_insn *insn)
        }
 
        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;