[PATCH bpf-next v1 10/10] bpf: fix env->peak_states computation

[Eduard Zingerman <eddyz87@gmail.com>]

Compute env->peak_states as a maximum value of sum of
env->explored_states and env->free_list size.

Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
---
 include/linux/bpf_verifier.h |  2 ++
 kernel/bpf/verifier.c        | 15 +++++++++++++--
 2 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/include/linux/bpf_verifier.h b/include/linux/bpf_verifier.h
index f920af30eb06..bbd013c38ff9 100644
--- a/include/linux/bpf_verifier.h
+++ b/include/linux/bpf_verifier.h
@@ -772,6 +772,8 @@ struct bpf_verifier_env {
 	u32 peak_states;
 	/* longest register parentage chain walked for liveness marking */
 	u32 longest_mark_read_walk;
+	u32 free_list_size;
+	u32 explored_states_size;
 	bpfptr_t fd_array;
 
 	/* bit mask to keep track of whether a register has been accessed
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index eadd404ab9ab..b92d5eb47083 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -1598,6 +1598,14 @@ static struct bpf_reference_state *find_lock_state(struct bpf_verifier_state *st
 	return NULL;
 }
 
+static void update_peak_states(struct bpf_verifier_env *env)
+{
+	u32 cur_states;
+
+	cur_states = env->explored_states_size + env->free_list_size;
+	env->peak_states = max(env->peak_states, cur_states);
+}
+
 static void free_func_state(struct bpf_func_state *state)
 {
 	if (!state)
@@ -1659,7 +1667,7 @@ static void maybe_free_verifier_state(struct bpf_verifier_env *env,
 		list_del(&sl->node);
 		free_verifier_state(&sl->state, false);
 		kfree(sl);
-		env->peak_states--;
+		env->free_list_size--;
 		sl = loop_entry_sl;
 	}
 }
@@ -18809,6 +18817,8 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
 			sl->in_free_list = true;
 			list_del(&sl->node);
 			list_add(&sl->node, &env->free_list);
+			env->free_list_size++;
+			env->explored_states_size--;
 			maybe_free_verifier_state(env, sl);
 		}
 	}
@@ -18835,7 +18845,8 @@ static int is_state_visited(struct bpf_verifier_env *env, int insn_idx)
 	if (!new_sl)
 		return -ENOMEM;
 	env->total_states++;
-	env->peak_states++;
+	env->explored_states_size++;
+	update_peak_states(env);
 	env->prev_jmps_processed = env->jmps_processed;
 	env->prev_insn_processed = env->insn_processed;
 
-- 
2.48.1