From df5703348813235874d851934e957c3723d71644 Mon Sep 17 00:00:00 2001
From: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Date: Wed, 1 Feb 2023 14:01:11 -0800
Subject: [PATCH] Bluetooth: L2CAP: Fix potential user-after-free
Git-commit: df5703348813235874d851934e957c3723d71644
Patch-mainline: v6.3-rc1
References: git-fixes
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>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
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;
--
2.35.3