netdev - [PATCH net 3/4] wireguard: socket: free skb in send6 when ipv6 is disabled

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Message-Id: <20220330013127.426620-4-Jason@zx2c4.com>
Date:   Tue, 29 Mar 2022 21:31:26 -0400
From:   "Jason A. Donenfeld" <Jason@...c4.com>
To:     netdev@...r.kernel.org, davem@...emloft.net, kuba@...nel.org
Cc:     Wang Hai <wanghai38@...wei.com>, stable@...r.kernel.org,
        "Jason A . Donenfeld" <Jason@...c4.com>
Subject: [PATCH net 3/4] wireguard: socket: free skb in send6 when ipv6 is disabled

From: Wang Hai <wanghai38@...wei.com>

I got a memory leak report:

unreferenced object 0xffff8881191fc040 (size 232):
  comm "kworker/u17:0", pid 23193, jiffies 4295238848 (age 3464.870s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [<ffffffff814c3ef4>] slab_post_alloc_hook+0x84/0x3b0
    [<ffffffff814c8977>] kmem_cache_alloc_node+0x167/0x340
    [<ffffffff832974fb>] __alloc_skb+0x1db/0x200
    [<ffffffff82612b5d>] wg_socket_send_buffer_to_peer+0x3d/0xc0
    [<ffffffff8260e94a>] wg_packet_send_handshake_initiation+0xfa/0x110
    [<ffffffff8260ec81>] wg_packet_handshake_send_worker+0x21/0x30
    [<ffffffff8119c558>] process_one_work+0x2e8/0x770
    [<ffffffff8119ca2a>] worker_thread+0x4a/0x4b0
    [<ffffffff811a88e0>] kthread+0x120/0x160
    [<ffffffff8100242f>] ret_from_fork+0x1f/0x30

In function wg_socket_send_buffer_as_reply_to_skb() or wg_socket_send_
buffer_to_peer(), the semantics of send6() is required to free skb. But
when CONFIG_IPV6 is disable, kfree_skb() is missing. This patch adds it
to fix this bug.

Signed-off-by: Wang Hai <wanghai38@...wei.com>
Fixes: e7096c131e51 ("net: WireGuard secure network tunnel")
Cc: stable@...r.kernel.org
Signed-off-by: Jason A. Donenfeld <Jason@...c4.com>
---
 drivers/net/wireguard/socket.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/wireguard/socket.c b/drivers/net/wireguard/socket.c
index 6f07b949cb81..467eef0e563b 100644
--- a/drivers/net/wireguard/socket.c
+++ b/drivers/net/wireguard/socket.c
@@ -160,6 +160,7 @@ static int send6(struct wg_device *wg, struct sk_buff *skb,
 	rcu_read_unlock_bh();
 	return ret;
 #else
+	kfree_skb(skb);
 	return -EAFNOSUPPORT;
 #endif
 }
-- 
2.35.1