| Message ID | 20231206123118.GA15625@ubuntu (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | atm: Fix Use-After-Free in do_vcc_ioctl | expand |
On Wed, 6 Dec 2023 04:31:18 -0800 Hyunwoo Kim wrote: > + if ((skb = skb_peek(&sk->sk_receive_queue)) != NULL) > + amount = skb->len; Please run checkpatch, no assignments in if () statements. This is better written with a ternary op IMO, anyway: skb = peek() amount = skb ? skb->len : 0; When you repost please put [PATCH net v2] as the tag.
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:
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@theori.io> --- net/atm/ioctl.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-)