| Message ID | 20231213041056.GA519680@v4bel-B760M-AORUS-ELITE-AX (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 189ff16722ee36ced4d2a2469d4ab65a8fee4198 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [v3] appletalk: Fix Use-After-Free in atalk_ioctl | expand |
Hello: This patch was applied to netdev/net.git (main) by Paolo Abeni <pabeni@redhat.com>: On Tue, 12 Dec 2023 23:10:56 -0500 you wrote: > 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. > > [...] Here is the summary with links: - [v3] appletalk: Fix Use-After-Free in atalk_ioctl https://git.kernel.org/netdev/net/c/189ff16722ee You are awesome, thank you!
diff --git a/net/appletalk/ddp.c b/net/appletalk/ddp.c index 9ba04a69ec2a..a852ec093fa8 100644 --- a/net/appletalk/ddp.c +++ b/net/appletalk/ddp.c @@ -1775,15 +1775,14 @@ static int atalk_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg) break; } case TIOCINQ: { - /* - * 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); + struct sk_buff *skb; 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; }
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@theori.io> --- v1 -> v2: Change the code style v2 -> v3: Delete old comments --- net/appletalk/ddp.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)