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Bluetooth: L2CAP: Fix potential user-after-free

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This fixes all instances of which requires to allocate a buffer calling
alloc_skb which may release the chan lock and reacquire later which
makes it possible that the chan is disconnected in the meantime.

Fixes: a6a5568c03 ("Bluetooth: Lock the L2CAP channel when sending")
Reported-by: Alexander Coffin <alex.coffin@matician.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
This commit is contained in:
Luiz Augusto von Dentz 2023-02-01 14:01:11 -08:00
parent 2394186a2c
commit df57033488
2 changed files with 8 additions and 24 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

24
net/bluetooth/l2cap_core.c
View file

@ -2683,14 +2683,6 @@ int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len)
if (IS_ERR(skb))
return PTR_ERR(skb);
/* Channel lock is released before requesting new skb and then
* reacquired thus we need to recheck channel state.
*/
if (chan->state != BT_CONNECTED) {
kfree_skb(skb);
return -ENOTCONN;
}
l2cap_do_send(chan, skb);
return len;
}
@ -2735,14 +2727,6 @@ int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len)
if (IS_ERR(skb))
return PTR_ERR(skb);
/* Channel lock is released before requesting new skb and then
* reacquired thus we need to recheck channel state.
*/
if (chan->state != BT_CONNECTED) {
kfree_skb(skb);
return -ENOTCONN;
}
l2cap_do_send(chan, skb);
err = len;
break;
@ -2763,14 +2747,6 @@ int l2cap_chan_send(struct l2cap_chan *chan, struct msghdr *msg, size_t len)
*/
err = l2cap_segment_sdu(chan, &seg_queue, msg, len);
/* The channel could have been closed while segmenting,
* check that it is still connected.
*/
if (chan->state != BT_CONNECTED) {
__skb_queue_purge(&seg_queue);
err = -ENOTCONN;
}
if (err)
break;

8
net/bluetooth/l2cap_sock.c
View file

@ -1624,6 +1624,14 @@ static struct sk_buff *l2cap_sock_alloc_skb_cb(struct l2cap_chan *chan,
if (!skb)
return ERR_PTR(err);
/* Channel lock is released before requesting new skb and then
* reacquired thus we need to recheck channel state.
*/
if (chan->state != BT_CONNECTED) {
kfree_skb(skb);
return ERR_PTR(-ENOTCONN);
}
skb->priority = sk->sk_priority;
bt_cb(skb)->l2cap.chan = chan;