netdev - [PATCH] net: netrom: fix memory leak in nr

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Message-ID: <20251129034232.405203-1-kartikey406@gmail.com>
Date: Sat, 29 Nov 2025 09:12:32 +0530
From: Deepanshu Kartikey <kartikey406@...il.com>
To: davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com,
	horms@...nel.org
Cc: linux-hams@...r.kernel.org,
	netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Deepanshu Kartikey <kartikey406@...il.com>,
	syzbot+d7abc36bbbb6d7d40b58@...kaller.appspotmail.com
Subject: [PATCH] net: netrom: fix memory leak in nr_output()

When nr_output() fragments a large packet, it calls sock_alloc_send_skb()
in a loop to allocate skbs for each fragment. If this allocation fails,
the function returns without freeing the original skb that was passed in,
causing a memory leak.

Add the missing kfree_skb() call before returning on allocation failure.

Reported-by: syzbot+d7abc36bbbb6d7d40b58@...kaller.appspotmail.com
Tested-by: syzbot+d7abc36bbbb6d7d40b58@...kaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=d7abc36bbbb6d7d40b58
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Deepanshu Kartikey <kartikey406@...il.com>
---
 net/netrom/nr_out.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/netrom/nr_out.c b/net/netrom/nr_out.c
index 5e531394a724..2b3cbceb0b52 100644
--- a/net/netrom/nr_out.c
+++ b/net/netrom/nr_out.c
@@ -43,8 +42,11 @@ void nr_output(struct sock *sk, struct sk_buff *skb)
 		frontlen = skb_headroom(skb);
 
 		while (skb->len > 0) {
-			if ((skbn = sock_alloc_send_skb(sk, frontlen + NR_MAX_PACKET_SIZE, 0, &err)) == NULL)
			skbn = sock_alloc_send_skb(sk, frontlen + NR_MAX_PACKET_SIZE, 0, &err);
			if (skbn == NULL) {
+				kfree_skb(skb);
 				return;
+			}
 
 			skb_reserve(skbn, frontlen);
 
-- 
2.43.0