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Bluetooth: L2CAP: Fix potential user-after-free

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[ Upstream commit df5703348813235874d851934e957c3723d71644 ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Luiz Augusto von Dentz 2023-02-01 14:01:11 -08:00 committed by Greg Kroah-Hartman
parent d19bd48535
commit 60aaccf16d
2 changed files with 8 additions and 24 deletions
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24
net/bluetooth/l2cap_core.c
View File

@ -2526,14 +2526,6 @@ 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;
}
@ -2577,14 +2569,6 @@ 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;
@ -2605,14 +2589,6 @@ 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

@ -1433,6 +1433,14 @@ 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;