netdev - [PATCH v1 net] tcp: Fix use-after-free of nreq in reqsk_timer

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Message-ID: <20241123174236.62438-1-kuniyu@amazon.com>
Date: Sat, 23 Nov 2024 09:42:36 -0800
From: Kuniyuki Iwashima <kuniyu@...zon.com>
To: "David S. Miller" <davem@...emloft.net>, Eric Dumazet
	<edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>
CC: Kuniyuki Iwashima <kuniyu@...zon.com>, Kuniyuki Iwashima
	<kuni1840@...il.com>, <netdev@...r.kernel.org>, Liu Jian
	<liujian56@...wei.com>
Subject: [PATCH v1 net] tcp: Fix use-after-free of nreq in reqsk_timer_handler().

The cited commit replaced inet_csk_reqsk_queue_drop_and_put() with
__inet_csk_reqsk_queue_drop() and reqsk_put() in reqsk_timer_handler().

Then, oreq should be passed to reqsk_put() instead of req; otherwise
use-after-free of nreq could happen when reqsk is migrated but the
retry attempt failed (e.g. due to timeout).

Let's pass oreq to reqsk_put().

Fixes: e8c526f2bdf1 ("tcp/dccp: Don't use timer_pending() in reqsk_queue_unlink().")
Reported-by: Liu Jian <liujian56@...wei.com>
Closes: https://lore.kernel.org/netdev/1284490f-9525-42ee-b7b8-ccadf6606f6d@huawei.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@...zon.com>
---
 net/ipv4/inet_connection_sock.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 491c2c6b683e..6872b5aff73e 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -1191,7 +1191,7 @@ static void reqsk_timer_handler(struct timer_list *t)
 
 drop:
 	__inet_csk_reqsk_queue_drop(sk_listener, oreq, true);
-	reqsk_put(req);
+	reqsk_put(oreq);
 }
 
 static bool reqsk_queue_hash_req(struct request_sock *req,
-- 
2.39.5 (Apple Git-154)