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* [PATCH] Bluetooth: L2CAP: Fix potential user-after-free
@ 2023-02-01 22:07 Luiz Augusto von Dentz
  2023-02-01 22:36 ` bluez.test.bot
  2023-02-02 21:20 ` [PATCH] " patchwork-bot+bluetooth
  0 siblings, 2 replies; 6+ messages in thread
From: Luiz Augusto von Dentz @ 2023-02-01 22:07 UTC (permalink / raw)
  To: linux-bluetooth

From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

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: a6a5568c03c4 ("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>
---
 net/bluetooth/l2cap_core.c | 24 ------------------------
 net/bluetooth/l2cap_sock.c |  8 ++++++++
 2 files changed, 8 insertions(+), 24 deletions(-)

diff --git a/net/bluetooth/l2cap_core.c b/net/bluetooth/l2cap_core.c
index a3e0dc6a6e73..adfc3ea06d08 100644
--- a/net/bluetooth/l2cap_core.c
+++ b/net/bluetooth/l2cap_core.c
@@ -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;
 
diff --git a/net/bluetooth/l2cap_sock.c b/net/bluetooth/l2cap_sock.c
index ca8f07f3542b..eebe256104bc 100644
--- a/net/bluetooth/l2cap_sock.c
+++ b/net/bluetooth/l2cap_sock.c
@@ -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;
-- 
2.37.3


^ permalink raw reply related	[flat|nested] 6+ messages in thread
end of thread, other threads:[~2023-02-15  0:58 UTC | newest]

Thread overview: 6+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2023-02-01 22:07 [PATCH] Bluetooth: L2CAP: Fix potential user-after-free Luiz Augusto von Dentz
2023-02-01 22:36 ` bluez.test.bot
2023-02-01 23:47   ` Luiz Augusto von Dentz
2023-02-15  0:44     ` Alexander Coffin
2023-02-15  0:58       ` Luiz Augusto von Dentz
2023-02-02 21:20 ` [PATCH] " patchwork-bot+bluetooth

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