| Message ID | 20231209090509.GA401342@v4bel-B760M-AORUS-ELITE-AX (mailing list archive) |
|---|---|
| State | Superseded |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net,v2] atm: Fix Use-After-Free in do_vcc_ioctl | expand |
On Sat, Dec 9, 2023 at 10:05 AM Hyunwoo Kim <v4bel@theori.io> wrote: > > 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> > --- > v1 -> v2: Change the code style > --- > net/atm/ioctl.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/net/atm/ioctl.c b/net/atm/ioctl.c > index 838ebf0cabbf..b7684abcf458 100644 > --- a/net/atm/ioctl.c > +++ b/net/atm/ioctl.c > @@ -72,15 +72,18 @@ static int do_vcc_ioctl(struct socket *sock, unsigned int cmd, > goto done; > case SIOCINQ: > { > + long amount; > struct sk_buff *skb; This should be "int amount;", and should be put after the " struct sk_buff *skb;" line for proper style. > > if (sock->state != SS_CONNECTED) { > error = -EINVAL; > goto done; > } > + spin_lock_irq(&sk->sk_receive_queue.lock); > skb = skb_peek(&sk->sk_receive_queue); > - error = put_user(skb ? skb->len : 0, > - (int __user *)argp) ? -EFAULT : 0; > + amount = skb ? skb->len : 0; > + 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 >
diff --git a/net/atm/ioctl.c b/net/atm/ioctl.c index 838ebf0cabbf..b7684abcf458 100644 --- a/net/atm/ioctl.c +++ b/net/atm/ioctl.c @@ -72,15 +72,18 @@ static int do_vcc_ioctl(struct socket *sock, unsigned int cmd, goto done; case SIOCINQ: { + long amount; struct sk_buff *skb; if (sock->state != SS_CONNECTED) { error = -EINVAL; goto done; } + spin_lock_irq(&sk->sk_receive_queue.lock); skb = skb_peek(&sk->sk_receive_queue); - error = put_user(skb ? skb->len : 0, - (int __user *)argp) ? -EFAULT : 0; + amount = skb ? skb->len : 0; + 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> --- v1 -> v2: Change the code style --- net/atm/ioctl.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)