Subject: [PATCH net] net: Fix memory leak in ieee802154_raw_deliver

From: Takeshi Misawa <[email-masked]>
Date: Thu, 5 Aug 2021 16:54:14 +0900

If IEEE-802.15.4-RAW is closed before receive skb, skb is leaked.
Fix this, by freeing sk_receive_queue in sk->sk_destruct().

syzbot report:
BUG: memory leak
unreferenced object 0xffff88810f644600 (size 232):
  comm "softirq", pid 0, jiffies 4294967032 (age 81.270s)
  hex dump (first 32 bytes):
    10 7d 4b 12 81 88 ff ff 10 7d 4b 12 81 88 ff ff  .}K......}K.....
    00 00 00 00 00 00 00 00 40 7c 4b 12 81 88 ff ff  ........@|K.....
  backtrace:
    [<ffffffff83651d4a>] skb_clone+0xaa/0x2b0 net/core/skbuff.c:1496
    [<ffffffff83fe1b80>] ieee802154_raw_deliver net/ieee802154/socket.c:369 [inline]
    [<ffffffff83fe1b80>] ieee802154_rcv+0x100/0x340 net/ieee802154/socket.c:1070
    [<ffffffff8367cc7a>] __netif_receive_skb_one_core+0x6a/0xa0 net/core/dev.c:5384
    [<ffffffff8367cd07>] __netif_receive_skb+0x27/0xa0 net/core/dev.c:5498
    [<ffffffff8367cdd9>] netif_receive_skb_internal net/core/dev.c:5603 [inline]
    [<ffffffff8367cdd9>] netif_receive_skb+0x59/0x260 net/core/dev.c:5662
    [<ffffffff83fe6302>] ieee802154_deliver_skb net/mac802154/rx.c:29 [inline]
    [<ffffffff83fe6302>] ieee802154_subif_frame net/mac802154/rx.c:102 [inline]
    [<ffffffff83fe6302>] __ieee802154_rx_handle_packet net/mac802154/rx.c:212 [inline]
    [<ffffffff83fe6302>] ieee802154_rx+0x612/0x620 net/mac802154/rx.c:284
    [<ffffffff83fe59a6>] ieee802154_tasklet_handler+0x86/0xa0 net/mac802154/main.c:35
    [<ffffffff81232aab>] tasklet_action_common.constprop.0+0x5b/0x100 kernel/softirq.c:557
    [<ffffffff846000bf>] __do_softirq+0xbf/0x2ab kernel/softirq.c:345
    [<ffffffff81232f4c>] do_softirq kernel/softirq.c:248 [inline]
    [<ffffffff81232f4c>] do_softirq+0x5c/0x80 kernel/softirq.c:235
    [<ffffffff81232fc1>] __local_bh_enable_ip+0x51/0x60 kernel/softirq.c:198
    [<ffffffff8367a9a4>] local_bh_enable include/linux/bottom_half.h:32 [inline]
    [<ffffffff8367a9a4>] rcu_read_unlock_bh include/linux/rcupdate.h:745 [inline]
    [<ffffffff8367a9a4>] __dev_queue_xmit+0x7f4/0xf60 net/core/dev.c:4221
    [<ffffffff83fe2db4>] raw_sendmsg+0x1f4/0x2b0 net/ieee802154/socket.c:295
    [<ffffffff8363af16>] sock_sendmsg_nosec net/socket.c:654 [inline]
    [<ffffffff8363af16>] sock_sendmsg+0x56/0x80 net/socket.c:674
    [<ffffffff8363deec>] __sys_sendto+0x15c/0x200 net/socket.c:1977
    [<ffffffff8363dfb6>] __do_sys_sendto net/socket.c:1989 [inline]
    [<ffffffff8363dfb6>] __se_sys_sendto net/socket.c:1985 [inline]
    [<ffffffff8363dfb6>] __x64_sys_sendto+0x26/0x30 net/socket.c:1985

Fixes: 9ec767160357 ("net: add IEEE 802.15.4 socket family implementation")
Reported-and-tested-by: [email-masked]
Signed-off-by: Takeshi Misawa <[email-masked]>
---
Dear David Howells, Jakub Kicinski

syzbot reported memory leak in ieee802154_raw_deliver.

I send a patch that passed syzbot reproducer test.
Please consider this memory leak and patch.

syzbot link:
https://syzkaller.appspot.com/bug?id=8dd3bcb1dc757587adfb4dbb810fd24dd990283f

Regards.
---
 net/ieee802154/socket.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/ieee802154/socket.c b/net/ieee802154/socket.c
index a45a0401adc5..c25f7617770c 100644
--- a/net/ieee802154/socket.c
+++ b/net/ieee802154/socket.c
@@ -984,6 +984,11 @@ static const struct proto_ops ieee802154_dgram_ops = {
 	.sendpage	   = sock_no_sendpage,
 };
 
+static void ieee802154_sock_destruct(struct sock *sk)
+{
+	skb_queue_purge(&sk->sk_receive_queue);
+}
+
 /* Create a socket. Initialise the socket, blank the addresses
  * set the state.
  */
@@ -1024,7 +1029,7 @@ static int ieee802154_create(struct net *net, struct socket *sock,
 	sock->ops = ops;
 
 	sock_init_data(sock, sk);
-	/* FIXME: sk->sk_destruct */
+	sk->sk_destruct = ieee802154_sock_destruct;
 	sk->sk_family = PF_IEEE802154;
 
 	/* Checksums on by default */
-- 
2.25.1