From: Kuniyuki Iwashima <kuniyu@amazon.com>
Date: Mon, 3 Apr 2023 12:49:59 -0700
Subject: [PATCH] ping: Fix potentail NULL deref for /proc/net/icmp.
References: bsc#1012628
Patch-mainline: 6.2.11
Git-commit: ab5fb73ffa01072b4d8031cc05801fa1cb653bee

[ Upstream commit ab5fb73ffa01072b4d8031cc05801fa1cb653bee ]

After commit dbca1596bbb0 ("ping: convert to RCU lookups, get rid
of rwlock"), we use RCU for ping sockets, but we should use spinlock
for /proc/net/icmp to avoid a potential NULL deref mentioned in
the previous patch.

Let's go back to using spinlock there.

Note we can convert ping sockets to use hlist instead of hlist_nulls
because we do not use SLAB_TYPESAFE_BY_RCU for ping sockets.

Fixes: dbca1596bbb0 ("ping: convert to RCU lookups, get rid of rwlock")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 net/ipv4/ping.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 409ec2a1..5178a3f3 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -1089,13 +1089,13 @@ static struct sock *ping_get_idx(struct seq_file *seq, loff_t pos)
 }
 
 void *ping_seq_start(struct seq_file *seq, loff_t *pos, sa_family_t family)
-	__acquires(RCU)
+	__acquires(ping_table.lock)
 {
 	struct ping_iter_state *state = seq->private;
 	state->bucket = 0;
 	state->family = family;
 
-	rcu_read_lock();
+	spin_lock(&ping_table.lock);
 
 	return *pos ? ping_get_idx(seq, *pos-1) : SEQ_START_TOKEN;
 }
@@ -1121,9 +1121,9 @@ void *ping_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 EXPORT_SYMBOL_GPL(ping_seq_next);
 
 void ping_seq_stop(struct seq_file *seq, void *v)
-	__releases(RCU)
+	__releases(ping_table.lock)
 {
-	rcu_read_unlock();
+	spin_unlock(&ping_table.lock);
 }
 EXPORT_SYMBOL_GPL(ping_seq_stop);
 
-- 
2.35.3