Subject: [PATCH 10/48] bpf/verifier: reject BPF_ALU64|BPF_END

From: Edward Cree <[email-masked]>
Date: Fri, 15 Sep 2017 14:37:38 +0100

[ Upstream commit e67b8a685c7c984e834e3181ef4619cd7025a136 ]

Neither ___bpf_prog_run nor the JITs accept it.
Also adds a new test case.

Fixes: 17a5267067f3 ("bpf: verifier (add verifier core)")
Signed-off-by: Edward Cree <[email-masked]>
Acked-by: Alexei Starovoitov <[email-masked]>
Acked-by: Daniel Borkmann <[email-masked]>
Signed-off-by: David S. Miller <[email-masked]>
---
 kernel/bpf/verifier.c                       |  3 ++-
 tools/testing/selftests/bpf/test_verifier.c | 16 ++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 664d93972373..3940019b9740 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1978,7 +1978,8 @@ static int check_alu_op(struct bpf_verifier_env *env, struct bpf_insn *insn)
 			}
 		} else {
 			if (insn->src_reg != BPF_REG_0 || insn->off != 0 ||
-			    (insn->imm != 16 && insn->imm != 32 && insn->imm != 64)) {
+			    (insn->imm != 16 && insn->imm != 32 && insn->imm != 64) ||
+			    BPF_CLASS(insn->code) == BPF_ALU64) {
 				verbose("BPF_END uses reserved fields\n");
 				return -EINVAL;
 			}
diff --git a/tools/testing/selftests/bpf/test_verifier.c b/tools/testing/selftests/bpf/test_verifier.c
index d3ed7324105e..48c145eeeaf7 100644
--- a/tools/testing/selftests/bpf/test_verifier.c
+++ b/tools/testing/selftests/bpf/test_verifier.c
@@ -6009,6 +6009,22 @@ static struct bpf_test tests[] = {
 		.result = REJECT,
 		.result_unpriv = REJECT,
 	},
+	{
+		"invalid 64-bit BPF_END",
+		.insns = {
+			BPF_MOV32_IMM(BPF_REG_0, 0),
+			{
+				.code  = BPF_ALU64 | BPF_END | BPF_TO_LE,
+				.dst_reg = BPF_REG_0,
+				.src_reg = 0,
+				.off   = 0,
+				.imm   = 32,
+			},
+			BPF_EXIT_INSN(),
+		},
+		.errstr = "BPF_END uses reserved fields",
+		.result = REJECT,
+	},
 };
 
 static int probe_filter_length(const struct bpf_insn *fp)
-- 
2.13.6