Subject: [PATCH v2 bpf-next 1/3] bpf: bump jmp sequence limit

From: Alexei Starovoitov <[email-masked]>
Date: Tue, 21 May 2019 20:14:19 -0700

The limit of 1024 subsequent jumps was causing otherwise valid
programs to be rejected. Bump it to 8192 and make the error more verbose.

Signed-off-by: Alexei Starovoitov <[email-masked]>
Acked-by: Andrii Nakryiko <[email-masked]>
---
 kernel/bpf/verifier.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 082f6eefb1c4..4113e829616d 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -176,7 +176,7 @@ struct bpf_verifier_stack_elem {
 	struct bpf_verifier_stack_elem *next;
 };
 
-#define BPF_COMPLEXITY_LIMIT_STACK	1024
+#define BPF_COMPLEXITY_LIMIT_JMP_SEQ	8192
 #define BPF_COMPLEXITY_LIMIT_STATES	64
 
 #define BPF_MAP_PTR_UNPRIV	1UL
@@ -782,8 +782,9 @@ static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
 	if (err)
 		goto err;
 	elem->st.speculative |= speculative;
-	if (env->stack_size > BPF_COMPLEXITY_LIMIT_STACK) {
-		verbose(env, "BPF program is too complex\n");
+	if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
+		verbose(env, "The sequence of %d jumps is too complex.\n",
+			env->stack_size);
 		goto err;
 	}
 	return &elem->st;
-- 
2.20.0