From: Sidraya Jayagond <sidraya@xxxxxxxxxxxxx>
Passing MSG_PEEK flag to skb_recv_datagram() increments skb refcount
(skb->users) and iucv_sock_recvmsg() does not decrement skb refcount
at exit.
This results in skb memory leak in skb_queue_purge() and WARN_ON in
iucv_sock_destruct() during socket close. To fix this decrease
skb refcount by one if MSG_PEEK is set in order to prevent memory
leak and WARN_ON.
WARNING: CPU: 2 PID: 6292 at net/iucv/af_iucv.c:286 iucv_sock_destruct+0x144/0x1a0 [af_iucv]
CPU: 2 PID: 6292 Comm: afiucv_test_msg Kdump: loaded Tainted: G W 6.10.0-rc7 #1
Hardware name: IBM 3931 A01 704 (z/VM 7.3.0)
Call Trace:
[<001587c682c4aa98>] iucv_sock_destruct+0x148/0x1a0 [af_iucv]
[<001587c682c4a9d0>] iucv_sock_destruct+0x80/0x1a0 [af_iucv]
[<001587c704117a32>] __sk_destruct+0x52/0x550
[<001587c704104a54>] __sock_release+0xa4/0x230
[<001587c704104c0c>] sock_close+0x2c/0x40
[<001587c702c5f5a8>] __fput+0x2e8/0x970
[<001587c7024148c4>] task_work_run+0x1c4/0x2c0
[<001587c7023b0716>] do_exit+0x996/0x1050
[<001587c7023b13aa>] do_group_exit+0x13a/0x360
[<001587c7023b1626>] __s390x_sys_exit_group+0x56/0x60
[<001587c7022bccca>] do_syscall+0x27a/0x380
[<001587c7049a6a0c>] __do_syscall+0x9c/0x160
[<001587c7049ce8a8>] system_call+0x70/0x98
Last Breaking-Event-Address:
[<001587c682c4a9d4>] iucv_sock_destruct+0x84/0x1a0 [af_iucv]
Fixes: eac3731bd04c ("[S390]: Add AF_IUCV socket support")
Reviewed-by: Alexandra Winter <wintera@xxxxxxxxxxxxx>
Reviewed-by: Thorsten Winkler <twinkler@xxxxxxxxxxxxx>
Signed-off-by: Sidraya Jayagond <sidraya@xxxxxxxxxxxxx>
Signed-off-by: Alexandra Winter <wintera@xxxxxxxxxxxxx>
---
The following mailaddresses are no longer active:
Frank Pavlic <fpavlic@xxxxxxxxxx> (blamed_fixes:1/1=100%)
Martin Schwidefsky <schwidefsky@xxxxxxxxxx> (blamed_fixes:1/1=100%)
---
net/iucv/af_iucv.c | 26 +++++++++++++++++---------
1 file changed, 17 insertions(+), 9 deletions(-)
diff --git a/net/iucv/af_iucv.c b/net/iucv/af_iucv.c
index c00323fa9eb6..7929df08d4e0 100644
--- a/net/iucv/af_iucv.c
+++ b/net/iucv/af_iucv.c
@@ -1236,7 +1236,9 @@ static int iucv_sock_recvmsg(struct socket *sock, struct msghdr *msg,
return -EOPNOTSUPP;
/* receive/dequeue next skb:
- * the function understands MSG_PEEK and, thus, does not dequeue skb */
+ * the function understands MSG_PEEK and, thus, does not dequeue skb
+ * only refcount is increased.
+ */
skb = skb_recv_datagram(sk, flags, &err);
if (!skb) {
if (sk->sk_shutdown & RCV_SHUTDOWN)
@@ -1252,9 +1254,8 @@ static int iucv_sock_recvmsg(struct socket *sock, struct msghdr *msg,
cskb = skb;
if (skb_copy_datagram_msg(cskb, offset, msg, copied)) {
- if (!(flags & MSG_PEEK))
- skb_queue_head(&sk->sk_receive_queue, skb);
- return -EFAULT;
+ err = -EFAULT;
+ goto err_out;
}
/* SOCK_SEQPACKET: set MSG_TRUNC if recv buf size is too small */
@@ -1271,11 +1272,8 @@ static int iucv_sock_recvmsg(struct socket *sock, struct msghdr *msg,
err = put_cmsg(msg, SOL_IUCV, SCM_IUCV_TRGCLS,
sizeof(IUCV_SKB_CB(skb)->class),
(void *)&IUCV_SKB_CB(skb)->class);
- if (err) {
- if (!(flags & MSG_PEEK))
- skb_queue_head(&sk->sk_receive_queue, skb);
- return err;
- }
+ if (err)
+ goto err_out;
/* Mark read part of skb as used */
if (!(flags & MSG_PEEK)) {
@@ -1331,8 +1329,18 @@ static int iucv_sock_recvmsg(struct socket *sock, struct msghdr *msg,
/* SOCK_SEQPACKET: return real length if MSG_TRUNC is set */
if (sk->sk_type == SOCK_SEQPACKET && (flags & MSG_TRUNC))
copied = rlen;
+ if (flags & MSG_PEEK)
+ skb_unref(skb);
return copied;
+
+err_out:
+ if (!(flags & MSG_PEEK))
+ skb_queue_head(&sk->sk_receive_queue, skb);
+ else
+ skb_unref(skb);
+
+ return err;
}
static inline __poll_t iucv_accept_poll(struct sock *parent)
--
2.45.2
