netdev - [PATCH v2] appletalk: Fix Use-After-Free in atalk

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20231209095552.GA406496@v4bel-B760M-AORUS-ELITE-AX>
Date: Sat, 9 Dec 2023 04:55:52 -0500
From: Hyunwoo Kim <v4bel@...ori.io>
To: kuniyu@...zon.com, davem@...emloft.net, edumazet@...gle.com
Cc: v4bel@...ori.io, imv4bel@...il.com, kuba@...nel.org, pabeni@...hat.com,
	horms@...nel.org, dhowells@...hat.com, lukas.bulwahn@...il.com,
	mkl@...gutronix.de, netdev@...r.kernel.org
Subject: [PATCH v2] appletalk: Fix Use-After-Free in atalk_ioctl

Because atalk_ioctl() accesses sk->sk_receive_queue
without holding a sk->sk_receive_queue.lock, it can
cause a race with atalk_recvmsg().
A use-after-free for skb occurs with the following flow.
```
atalk_ioctl() -> skb_peek()
atalk_recvmsg() -> skb_recv_datagram() -> skb_free_datagram()
```
Add sk->sk_receive_queue.lock to atalk_ioctl() to fix this issue.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Hyunwoo Kim <v4bel@...ori.io>
---
v1 -> v2: Change the code style
---
 net/appletalk/ddp.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/net/appletalk/ddp.c b/net/appletalk/ddp.c
index 9ba04a69ec2a..016b8fb7f096 100644
--- a/net/appletalk/ddp.c
+++ b/net/appletalk/ddp.c
@@ -1775,15 +1775,17 @@ static int atalk_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 		break;
 	}
 	case TIOCINQ: {
+		long amount = 0;
+		struct sk_buff *skb;
 		/*
 		 * These two are safe on a single CPU system as only
 		 * user tasks fiddle here
 		 */
-		struct sk_buff *skb = skb_peek(&sk->sk_receive_queue);
-		long amount = 0;
-
+		spin_lock_irq(&sk->sk_receive_queue.lock);
+		skb = skb_peek(&sk->sk_receive_queue);
 		if (skb)
 			amount = skb->len - sizeof(struct ddpehdr);
+		spin_unlock_irq(&sk->sk_receive_queue.lock);
 		rc = put_user(amount, (int __user *)argp);
 		break;
 	}
-- 
2.25.1