linux-kernel - [PATCH v2] net: qrtr: fix memory leaks

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Date:   Fri, 23 Jul 2021 18:31:32 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     mani@...nel.org, davem@...emloft.net, kuba@...nel.org,
        loic.poulain@...aro.org, bjorn.andersson@...aro.org,
        xiyou.wangcong@...il.com, edumazet@...gle.com
Cc:     netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        Pavel Skripkin <paskripkin@...il.com>,
        syzbot+35a511c72ea7356cdcf3@...kaller.appspotmail.com
Subject: [PATCH v2] net: qrtr: fix memory leaks

Syzbot reported memory leak in qrtr. The problem was in unputted
struct sock. qrtr_local_enqueue() function calls qrtr_port_lookup()
which takes sock reference if port was found. Then there is the following
check:

if (!ipc || &ipc->sk == skb->sk) {
	...
	return -ENODEV;
}

Since we should drop the reference before returning from this function and
ipc can be non-NULL inside this if, we should add qrtr_port_put() inside
this if.

The similar corner case is in qrtr_endpoint_post() as Manivannan
reported. In case of sock_queue_rcv_skb() failure we need to put
port reference to avoid leaking struct sock pointer.

Fixes: e04df98adf7d ("net: qrtr: Remove receive worker")
Fixes: bdabad3e363d ("net: Add Qualcomm IPC router")
Reported-and-tested-by: syzbot+35a511c72ea7356cdcf3@...kaller.appspotmail.com
Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
---

Changes in v2:
	Added missing qrtr_port_put() in qrtr_endpoint_post() as Manivannan
	reported.

---
 net/qrtr/qrtr.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/net/qrtr/qrtr.c b/net/qrtr/qrtr.c
index b34358282f37..a8b2c9b21a8d 100644
--- a/net/qrtr/qrtr.c
+++ b/net/qrtr/qrtr.c
@@ -514,8 +514,10 @@ int qrtr_endpoint_post(struct qrtr_endpoint *ep, const void *data, size_t len)
 		if (!ipc)
 			goto err;
 
-		if (sock_queue_rcv_skb(&ipc->sk, skb))
+		if (sock_queue_rcv_skb(&ipc->sk, skb)) {
+			qrtr_port_put(ipc);
 			goto err;
+		}
 
 		qrtr_port_put(ipc);
 	}
@@ -850,6 +852,8 @@ static int qrtr_local_enqueue(struct qrtr_node *node, struct sk_buff *skb,
 
 	ipc = qrtr_port_lookup(to->sq_port);
 	if (!ipc || &ipc->sk == skb->sk) { /* do not send to self */
+		if (ipc)
+			qrtr_port_put(ipc);
 		kfree_skb(skb);
 		return -ENODEV;
 	}
-- 
2.32.0