[PATCH bpf-next v4 04/16] bpf: Prune verifier diagnostics when switching paths

[Kumar Kartikeya Dwivedi <memxor@gmail.com>]

Save the diagnostic event-log position with each verifier stack entry and
reset the environment-owned stream together with the normal verifier log
when a queued state is popped. Also reset the diagnostic stream after
successful subprogram verification even when level-2 logging preserves the
normal verifier log.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
---
 kernel/bpf/verifier.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 6ca366ff5037..2e915292265b 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -194,6 +194,7 @@ struct bpf_verifier_stack_elem {
 	struct bpf_verifier_stack_elem *next;
 	/* length of verifier log at the time this state was pushed on stack */
 	u32 log_pos;
+	u32 diag_log_pos;
 };
 
 #define BPF_COMPLEXITY_LIMIT_JMP_SEQ	8192
@@ -1700,6 +1701,7 @@ static int pop_stack(struct bpf_verifier_env *env, int *prev_insn_idx,
 		err = bpf_copy_verifier_state(cur, &head->st);
 		if (err)
 			return err;
+		bpf_diag_event_log_reset(env, head->diag_log_pos);
 	}
 	if (pop_log)
 		bpf_vlog_reset(&env->log, head->log_pos);
@@ -1743,6 +1745,7 @@ static struct bpf_verifier_state *push_stack(struct bpf_verifier_env *env,
 	elem->prev_insn_idx = prev_insn_idx;
 	elem->next = env->head;
 	elem->log_pos = env->log.end_pos;
+	elem->diag_log_pos = bpf_diag_event_log_pos(env);
 	env->head = elem;
 	env->stack_size++;
 	err = bpf_copy_verifier_state(&elem->st, cur);
@@ -2264,6 +2267,7 @@ static struct bpf_verifier_state *push_async_cb(struct bpf_verifier_env *env,
 	elem->prev_insn_idx = prev_insn_idx;
 	elem->next = env->head;
 	elem->log_pos = env->log.end_pos;
+	elem->diag_log_pos = bpf_diag_event_log_pos(env);
 	env->head = elem;
 	env->stack_size++;
 	if (env->stack_size > BPF_COMPLEXITY_LIMIT_JMP_SEQ) {
@@ -18566,8 +18570,11 @@ static int do_check_common(struct bpf_verifier_env *env, int subprog)
 
 	ret = do_check(env);
 out:
-	if (!ret && pop_log)
-		bpf_vlog_reset(&env->log, 0);
+	if (!ret) {
+		if (pop_log)
+			bpf_vlog_reset(&env->log, 0);
+		bpf_diag_event_log_reset(env, 0);
+	}
 	free_states(env);
 	return ret;
 }
-- 
2.53.0