[PATCH 6.6.y 0/2] CVE-2026-63974, CVE-2026-98297: backport fix series

[PATCH 6.6.y 0/2] CVE-2026-63974, CVE-2026-98297: backport fix series

[Artem Dinaburg]

Hi,

Please consider this backport series for CVE-2026-63974, CVE-2026-98297 to
6.6.y.

Apply the patches in this order:
1. Bluetooth: hci_sync: Set HCI_CMD_DRAIN_WORKQUEUE during device close (fix)
2. Bluetooth: hci_core: Fix queuing tx_work after workqueue is drained (fix)

Patch 1 marks the workqueue as draining during device close and waits for
earlier RCU-protected producers before draining it.

Patch 2 makes ACL, SCO and ISO transmit scheduling check that drain flag
under RCU, preventing new tx_work from being queued during close. The code
changes in both patches are identical to upstream.

The complete fix is already present in 6.12.y, 6.18.y and 7.2.y.

Build-tested only as part of a cumulative 6.6.y series on x86_64
(allmodconfig, CONFIG_WERROR=y); no runtime testing.

An LLM assisted with preparing these backports.

Thanks,
Artem Dinaburg

[PATCH 6.6.y 1/2] Bluetooth: hci_sync: Set HCI_CMD_DRAIN_WORKQUEUE during device close

[Artem Dinaburg]

From: Heitor Alves de Siqueira <halves@igalia.com>

[ Upstream commit 525daaea459fc215f432de1b8debbd9144bf97b0 ]

Since hci_dev_close_sync() can now be called during the reset path, we
should also set HCI_CMD_DRAIN_WORKQUEUE. This avoids queuing timeouts
while the hdev workqueue is being drained.

Fixes: 877afadad2dc ("Bluetooth: When HCI work queue is drained, only queue chained work")
Signed-off-by: Heitor Alves de Siqueira <halves@igalia.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Assisted-by: LLM
Signed-off-by: Artem Dinaburg <artem@trailofbits.com>
---
Hi,

Please consider this backport of the fix for CVE-2026-63974 to 6.6.y.

The code changes are identical to upstream.

The complete fix is already present in 6.12.y, 6.18.y and 7.2.y.

Build-tested only as part of a cumulative 6.6.y series on x86_64
(allmodconfig, CONFIG_WERROR=y); no runtime testing.

Thanks,
Artem Dinaburg

 net/bluetooth/hci_sync.c |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
index 607667cc357558ffefa812e1cf001ca923fdbf78..0c96e048d8816016c44f8d1b90c99f4addda8ed8 100644
--- a/net/bluetooth/hci_sync.c
+++ b/net/bluetooth/hci_sync.c
@@ -5349,6 +5349,12 @@ int hci_dev_close_sync(struct hci_dev *hdev)
 
 	bt_dev_dbg(hdev, "");
 
+	/* Set HCI_DRAIN_WORKQUEUE flag to prevent queuing work during
+	 * reset/close. See hci_cmd_work() and handle_cmd_cnt_and_timer().
+	 */
+	hci_dev_set_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE);
+	synchronize_rcu();
+
 	cancel_delayed_work(&hdev->power_off);
 	cancel_delayed_work(&hdev->ncmd_timer);
 	cancel_delayed_work(&hdev->le_scan_disable);
@@ -5367,6 +5373,7 @@ int hci_dev_close_sync(struct hci_dev *hdev)
 
 	if (!test_and_clear_bit(HCI_UP, &hdev->flags)) {
 		cancel_delayed_work_sync(&hdev->cmd_timer);
+		hci_dev_clear_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE);
 		return err;
 	}
 
@@ -5467,6 +5474,7 @@ int hci_dev_close_sync(struct hci_dev *hdev)
 	/* Clear flags */
 	hdev->flags &= BIT(HCI_RAW);
 	hci_dev_clear_volatile_flags(hdev);
+	hci_dev_clear_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE);
 
 	memset(hdev->eir, 0, sizeof(hdev->eir));
 	memset(hdev->dev_class, 0, sizeof(hdev->dev_class));

[PATCH 6.6.y 2/2] Bluetooth: hci_core: Fix queuing tx_work after workqueue is drained

[Artem Dinaburg]

From: ThangNN99 <ngocthang2710.1999@gmail.com>

[ Upstream commit 6610c6fe4b8936c232048e6049bf77c70a6f759c ]

hci_send_acl(), hci_send_sco() and hci_send_iso() queue hdev->tx_work
unconditionally. They can run from the L2CAP/SCO/ISO socket send path
while hci_dev_close_sync() is draining hdev->workqueue (HCIDEVDOWN
racing with a socket write). Since that queue_work() is not chained
work from the tx_work worker itself, __queue_work() sees the queue
marked __WQ_DRAINING, warns "cannot queue %ps on wq %s", and drops
the work:

  WARNING: CPU: 1 PID: 5985 at kernel/workqueue.c:2352 __queue_work
  Call Trace:
   queue_work_on
   l2cap_chan_send
   l2cap_sock_sendmsg
   ...

hci_dev_close_sync() already sets HCI_CMD_DRAIN_WORKQUEUE before
draining, but only hci_cmd_work() and handle_cmd_cnt_and_timer()
check it before queuing. Route the tx_work producers through the
same guard via a shared hci_sched_tx() helper.

Fixes: 525daaea459f ("Bluetooth: hci_sync: Set HCI_CMD_DRAIN_WORKQUEUE during device close")
Reported-by: syzbot+b6919040d9958e2fc1ae@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=b6919040d9958e2fc1ae
Signed-off-by: ThangNN99 <ngocthang2710.1999@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Assisted-by: LLM
Signed-off-by: Artem Dinaburg <artem@trailofbits.com>
---
Hi,

Please consider this backport of the fix for CVE-2026-98297 to 6.6.y.

The code changes are identical to upstream.

The complete fix is already present in 6.12.y, 6.18.y and 7.2.y.

Build-tested only as part of a cumulative 6.6.y series on x86_64
(allmodconfig, CONFIG_WERROR=y); no runtime testing.

Thanks,
Artem Dinaburg

 net/bluetooth/hci_core.c |   17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/net/bluetooth/hci_core.c b/net/bluetooth/hci_core.c
index d4fac0987dd8e6e03aa756788c80dc78bc9d8a86..3dcd8dff594603fc989182319fb84df97cc1c709 100644
--- a/net/bluetooth/hci_core.c
+++ b/net/bluetooth/hci_core.c
@@ -3233,6 +3233,17 @@ static void hci_queue_acl(struct hci_chan *chan, struct sk_buff_head *queue,
 	}
 }
 
+/* Queue hdev->tx_work, unless hdev->workqueue is being drained by
+ * hci_dev_close_sync(), which would otherwise WARN and drop the work.
+ */
+static void hci_sched_tx(struct hci_dev *hdev)
+{
+	rcu_read_lock();
+	if (!hci_dev_test_flag(hdev, HCI_CMD_DRAIN_WORKQUEUE))
+		queue_work(hdev->workqueue, &hdev->tx_work);
+	rcu_read_unlock();
+}
+
 void hci_send_acl(struct hci_chan *chan, struct sk_buff *skb, __u16 flags)
 {
 	struct hci_dev *hdev = chan->conn->hdev;
@@ -3241,7 +3252,7 @@ void hci_send_acl(struct hci_chan *chan, struct sk_buff *skb, __u16 flags)
 
 	hci_queue_acl(chan, &chan->data_q, skb, flags);
 
-	queue_work(hdev->workqueue, &hdev->tx_work);
+	hci_sched_tx(hdev);
 }
 
 /* Send SCO data */
@@ -3262,7 +3273,7 @@ void hci_send_sco(struct hci_conn *conn, struct sk_buff *skb)
 	hci_skb_pkt_type(skb) = HCI_SCODATA_PKT;
 
 	skb_queue_tail(&conn->data_q, skb);
-	queue_work(hdev->workqueue, &hdev->tx_work);
+	hci_sched_tx(hdev);
 }
 
 /* Send ISO data */
@@ -3335,7 +3346,7 @@ void hci_send_iso(struct hci_conn *conn, struct sk_buff *skb)
 
 	hci_queue_iso(conn, &conn->data_q, skb);
 
-	queue_work(hdev->workqueue, &hdev->tx_work);
+	hci_sched_tx(hdev);
 }
 
 /* ---- HCI TX task (outgoing data) ---- */

RE: CVE-2026-63974, CVE-2026-98297: backport fix series

[bluez.test.bot]

[-- Attachment #1: Type: text/plain, Size: 847 bytes --]

This is an automated email and please do not reply to this email.

Dear Submitter,

Thank you for submitting the patches to the linux bluetooth mailing list.
While preparing the CI tests, the patches you submitted couldn't be applied to the current HEAD of the repository.

----- Output -----

error: patch failed: net/bluetooth/hci_sync.c:5349
error: net/bluetooth/hci_sync.c: patch does not apply
hint: Use 'git am --show-current-patch=diff' to see the failed patch
hint: When you have resolved this problem, run "git am --continue".
hint: If you prefer to skip this patch, run "git am --skip" instead.
hint: To restore the original branch and stop patching, run "git am --abort".
hint: Disable this message with "git config set advice.mergeConflict false"

Please resolve the issue and submit the patches again.


---
Regards,
Linux Bluetooth