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Message-ID: <20231206123118.GA15625@ubuntu>
Date: Wed, 6 Dec 2023 04:31:18 -0800
From: Hyunwoo Kim <v4bel@...ori.io>
To: davem@...emloft.net, edumazet@...gle.com
Cc: v4bel@...ori.io, imv4bel@...il.com, kuba@...nel.org, pabeni@...hat.com,
netdev@...r.kernel.org
Subject: [PATCH] atm: Fix Use-After-Free in do_vcc_ioctl
Because do_vcc_ioctl() accesses sk->sk_receive_queue
without holding a sk->sk_receive_queue.lock, it can
cause a race with vcc_recvmsg().
A use-after-free for skb occurs with the following flow.
```
do_vcc_ioctl() -> skb_peek()
vcc_recvmsg() -> skb_recv_datagram() -> skb_free_datagram()
```
Add sk->sk_receive_queue.lock to do_vcc_ioctl() to fix this issue.
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Hyunwoo Kim <v4bel@...ori.io>
---
net/atm/ioctl.c | 10 +++++++---
1 file changed, 7 insertions(+), 3 deletions(-)
diff --git a/net/atm/ioctl.c b/net/atm/ioctl.c
index 838ebf0cabbf..62abe022f2bc 100644
--- a/net/atm/ioctl.c
+++ b/net/atm/ioctl.c
@@ -73,14 +73,18 @@ static int do_vcc_ioctl(struct socket *sock, unsigned int cmd,
case SIOCINQ:
{
struct sk_buff *skb;
+ long amount = 0;
if (sock->state != SS_CONNECTED) {
error = -EINVAL;
goto done;
}
- skb = skb_peek(&sk->sk_receive_queue);
- error = put_user(skb ? skb->len : 0,
- (int __user *)argp) ? -EFAULT : 0;
+
+ spin_lock_irq(&sk->sk_receive_queue.lock);
+ if ((skb = skb_peek(&sk->sk_receive_queue)) != NULL)
+ amount = skb->len;
+ spin_unlock_irq(&sk->sk_receive_queue.lock);
+ error = put_user(amount, (int __user *)argp) ? -EFAULT : 0;
goto done;
}
case ATM_SETSC:
--
2.25.1
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