Re: [PATCH] net/rose: Fix Use-After-Free in rose_ioctl
From: Eric Dumazet <edumazet@google.com>
Date: 2023-12-04 09:51:43
Also in:
linux-hams
On Mon, Dec 4, 2023 at 7:57 AM Hyunwoo Kim [off-list ref] wrote:
quoted hunk ↗ jump to hunk
Because rose_ioctl() accesses sk->sk_receive_queue without holding a lock_sock, it can cause a race with rose_accept(). A use-after-free for skb occurs with the following flow.rose_ioctl() -> skb_peek() rose_accept() -> skb_dequeue() -> kfree_skb()Add lock_sock to rose_ioctl() to fix this issue. Signed-off-by: Hyunwoo Kim <redacted> --- net/rose/af_rose.c | 2 ++ 1 file changed, 2 insertions(+)diff --git a/net/rose/af_rose.c b/net/rose/af_rose.c index 0cc5a4e19900..5fe9db64b6df 100644 --- a/net/rose/af_rose.c +++ b/net/rose/af_rose.c@@ -1316,8 +1316,10 @@ static int rose_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg) struct sk_buff *skb; long amount = 0L; /* These two are safe on a single CPU system as only user tasks fiddle here */ + lock_sock(sk);
This is not correct. You will have to lock sk->sk_receive_queue.lock instead. Look at rose_recvmsg() for the reason why locking the socket itself is not helping.
if ((skb = skb_peek(&sk->sk_receive_queue)) != NULL)
amount = skb->len;
+ release_sock(sk);
return put_user(amount, (unsigned int __user *) argp);
}
--
2.25.1