FAILED: patch "[PATCH] thunderbolt: Prevent XDomain delayed work use-after-free on" failed to apply to 6.1-stable tree

PATCH New [email protected] 2 participants 2 messages Jul 20 – Jul 27

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Stable branch Thunderbolt driver

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[email protected]

author maintainer

2026-07-20 14:59 UTC #0 lore raw

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x 2c5d2d3c3f70cde2565d7b279b544893a2035842
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026072001-pedometer-stifling-5aab@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 2c5d2d3c3f70cde2565d7b279b544893a2035842 Mon Sep 17 00:00:00 2001
From: Michael Bommarito <[email protected]>
Date: Wed, 27 May 2026 07:46:04 -0400
Subject: [PATCH] thunderbolt: Prevent XDomain delayed work use-after-free on
disconnect

tb_xdp_handle_request() runs on system_wq and queues xd->state_work via queue_delayed_work() in three request handlers:
PROPERTIES_CHANGED_REQUEST, UUID_REQUEST (via start_handshake), and LINK_STATE_CHANGE_REQUEST. Similarly, update_xdomain() queues xd->properties_changed_work when local properties change.

Concurrently, tb_xdomain_remove() calls stop_handshake() which does cancel_delayed_work_sync() on both delayed works. Later, tb_xdomain_unregister() calls device_unregister() which eventually frees the xdomain. Since commit 559c1e1e0134 ("thunderbolt: Run tb_xdp_handle_request() in system workqueue") moved the request handler off tb->wq, the handler and the remove path are no longer serialized. If queue_delayed_work() executes after cancel_delayed_work_sync() but before the xdomain is freed, the delayed work fires on a freed object.

Add xd->removing that tb_xdomain_remove() sets under xd->lock before calling stop_handshake(). Each external queue site holds the same lock and checks removing before calling queue_delayed_work(). This provides the mutual exclusion needed:
either the queue site acquires the lock first and queues work that the subsequent cancel will see, or the remove path acquires the lock first and the queue site observes removing == true and skips the queue.

Fixes 559c1e1e0134 ("thunderbolt: Run tb_xdp_handle_request() in system workqueue")

Cc [email protected]

Assisted-by Claude:claude-opus-4-7

Signed-off-by Michael Bommarito <[email protected]>

Signed-off-by Mika Westerberg <[email protected]>

drivers/thunderbolt/xdomain.c +31 ~~-10~~

index 781d88d06b93..fe6c5ac703f4 100644
@@ -803,9 +803,13 @@ static void tb_xdp_handle_request(struct work_struct *work)
 		 * the xdomain related to this connection as well in
 		 * case there is a change in services it offers.
 		 */
-		if (xd && device_is_registered(&xd->dev))
-			queue_delayed_work(tb->wq, &xd->state_work,
-					   msecs_to_jiffies(XDOMAIN_SHORT_TIMEOUT));
+		if (xd) {
+			mutex_lock(&xd->lock);
+			if (!xd->removing && device_is_registered(&xd->dev))
+				queue_delayed_work(tb->wq, &xd->state_work,
+						   msecs_to_jiffies(XDOMAIN_SHORT_TIMEOUT));
+			mutex_unlock(&xd->lock);
+		}
 		break;
 
 	case UUID_REQUEST_OLD:

@@ -818,8 +822,12 @@ static void tb_xdp_handle_request(struct work_struct *work)
 		 * received UUID request from the remote host.
 		 */
 		if (!ret && xd && xd->state == XDOMAIN_STATE_ERROR) {
-			dev_dbg(&xd->dev, "restarting handshake\n");
-			start_handshake(xd);
+			mutex_lock(&xd->lock);
+			if (!xd->removing) {
+				dev_dbg(&xd->dev, "restarting handshake\n");
+				start_handshake(xd);
+			}
+			mutex_unlock(&xd->lock);
 		}
 		break;

@@ -885,9 +893,13 @@ static void tb_xdp_handle_request(struct work_struct *work)
 
 			ret = tb_xdp_link_state_change_response(ctl, route,
 								sequence, 0);
-			xd->target_link_width = lsc->tlw;
-			queue_delayed_work(tb->wq, &xd->state_work,
-					   msecs_to_jiffies(XDOMAIN_SHORT_TIMEOUT));
+			mutex_lock(&xd->lock);
+			if (!xd->removing) {
+				xd->target_link_width = lsc->tlw;
+				queue_delayed_work(tb->wq, &xd->state_work,
+						   msecs_to_jiffies(XDOMAIN_SHORT_TIMEOUT));
+			}
+			mutex_unlock(&xd->lock);
 		} else {
 			tb_xdp_error_response(ctl, route, sequence,
 					      ERROR_NOT_READY);

@@ -971,8 +983,12 @@ static int update_xdomain(struct device *dev, void *data)
 
 	xd = tb_to_xdomain(dev);
 	if (xd) {
-		queue_delayed_work(xd->tb->wq, &xd->properties_changed_work,
-				   msecs_to_jiffies(50));
+		mutex_lock(&xd->lock);
+		if (!xd->removing)
+			queue_delayed_work(xd->tb->wq,
+					   &xd->properties_changed_work,
+					   msecs_to_jiffies(50));
+		mutex_unlock(&xd->lock);
 	}
 
 	return 0;

@@ -2200,6 +2216,11 @@ static int unregister_service(struct device *dev, void *data)
 void tb_xdomain_remove(struct tb_xdomain *xd)
 {
 	tb_xdomain_debugfs_remove(xd);
+
+	mutex_lock(&xd->lock);
+	xd->removing = true;
+	mutex_unlock(&xd->lock);
+
 	stop_handshake(xd);
 	tb_xdomain_link_exit(xd);

include/linux/thunderbolt.h +3 -0

index b5659f883517..feb1af175cfd 100644
@@ -213,6 +213,8 @@ enum tb_link_width {
  * @link_width: Width of the downstream facing link
  * @link_usb4: Downstream link is USB4
  * @is_unplugged: The XDomain is unplugged
+ * @removing: Set by tb_xdomain_remove() under @lock to prevent
+ *	      concurrent delayed work queueing
  * @needs_uuid: If the XDomain does not have @remote_uuid it will be
  *		queried first
  * @service_ids: Used to generate IDs for the services

@@ -262,6 +264,7 @@ struct tb_xdomain {
 	enum tb_link_width link_width;
 	bool link_usb4;
 	bool is_unplugged;
+	bool removing;
 	bool needs_uuid;
 	struct ida service_ids;
 	struct ida in_hopids;

Sasha Levin

maintainer

2026-07-27 12:19 UTC #1 lore raw

PATCH 1/1 thunderbolt: Prevent XDomain delayed work use-after-free on disconnect

From: Michael Bommarito <[email protected]>

[ Upstream commit 2c5d2d3c3f70cde2565d7b279b544893a2035842 ]

Fixes 559c1e1e0134 ("thunderbolt: Run tb_xdp_handle_request() in system workqueue")

Cc [email protected]

Assisted-by Claude:claude-opus-4-7

Signed-off-by Michael Bommarito <[email protected]>

Signed-off-by Mika Westerberg <[email protected]>

Signed-off-by Sasha Levin <[email protected]>

---
 drivers/thunderbolt/xdomain.c | 40 ++++++++++++++++++++++++++---------
 include/linux/thunderbolt.h   |  3 +++
 2 files changed, 33 insertions(+), 10 deletions(-)

drivers/thunderbolt/xdomain.c +30 ~~-10~~

index 8cfd7f0639e735..371911e2ae4281 100644
@@ -784,9 +784,13 @@ static void tb_xdp_handle_request(struct work_struct *work)
 		 * the xdomain related to this connection as well in
 		 * case there is a change in services it offers.
 		 */
-		if (xd && device_is_registered(&xd->dev))
-			queue_delayed_work(tb->wq, &xd->state_work,
-					   msecs_to_jiffies(XDOMAIN_SHORT_TIMEOUT));
+		if (xd) {
+			mutex_lock(&xd->lock);
+			if (!xd->removing && device_is_registered(&xd->dev))
+				queue_delayed_work(tb->wq, &xd->state_work,
+						   msecs_to_jiffies(XDOMAIN_SHORT_TIMEOUT));
+			mutex_unlock(&xd->lock);
+		}
 		break;
 
 	case UUID_REQUEST_OLD:

@@ -799,8 +803,12 @@ static void tb_xdp_handle_request(struct work_struct *work)
 		 * received UUID request from the remote host.
 		 */
 		if (!ret && xd && xd->state == XDOMAIN_STATE_ERROR) {
-			dev_dbg(&xd->dev, "restarting handshake\n");
-			start_handshake(xd);
+			mutex_lock(&xd->lock);
+			if (!xd->removing) {
+				dev_dbg(&xd->dev, "restarting handshake\n");
+				start_handshake(xd);
+			}
+			mutex_unlock(&xd->lock);
 		}
 		break;

@@ -828,9 +836,13 @@ static void tb_xdp_handle_request(struct work_struct *work)
 
 			ret = tb_xdp_link_state_change_response(ctl, route,
 								sequence, 0);
-			xd->target_link_width = lsc->tlw;
-			queue_delayed_work(tb->wq, &xd->state_work,
-					   msecs_to_jiffies(XDOMAIN_SHORT_TIMEOUT));
+			mutex_lock(&xd->lock);
+			if (!xd->removing) {
+				xd->target_link_width = lsc->tlw;
+				queue_delayed_work(tb->wq, &xd->state_work,
+						   msecs_to_jiffies(XDOMAIN_SHORT_TIMEOUT));
+			}
+			mutex_unlock(&xd->lock);
 		} else {
 			tb_xdp_error_response(ctl, route, sequence,
 					      ERROR_NOT_READY);

@@ -1978,6 +1990,10 @@ void tb_xdomain_remove(struct tb_xdomain *xd)
 {
 	tb_xdomain_debugfs_remove(xd);
 
+	mutex_lock(&xd->lock);
+	xd->removing = true;
+	mutex_unlock(&xd->lock);
+
 	stop_handshake(xd);
 
 	device_for_each_child_reverse(&xd->dev, xd, unregister_service);

@@ -2364,8 +2380,12 @@ static int update_xdomain(struct device *dev, void *data)
 
 	xd = tb_to_xdomain(dev);
 	if (xd) {
-		queue_delayed_work(xd->tb->wq, &xd->properties_changed_work,
-				   msecs_to_jiffies(50));
+		mutex_lock(&xd->lock);
+		if (!xd->removing)
+			queue_delayed_work(xd->tb->wq,
+					   &xd->properties_changed_work,
+					   msecs_to_jiffies(50));
+		mutex_unlock(&xd->lock);
 	}
 
 	return 0;

include/linux/thunderbolt.h +3 -0

index 90cd08ab2f5d20..98af9ad04cac1a 100644
@@ -189,6 +189,8 @@ void tb_unregister_property_dir(const char *key, struct tb_property_dir *dir);
  * @link_width: Width of the link (1 or 2)
  * @link_usb4: Downstream link is USB4
  * @is_unplugged: The XDomain is unplugged
+ * @removing: Set by tb_xdomain_remove() under @lock to prevent
+ *	      concurrent delayed work queueing
  * @needs_uuid: If the XDomain does not have @remote_uuid it will be
  *		queried first
  * @service_ids: Used to generate IDs for the services

@@ -237,6 +239,7 @@ struct tb_xdomain {
 	unsigned int link_width;
 	bool link_usb4;
 	bool is_unplugged;
+	bool removing;
 	bool needs_uuid;
 	struct ida service_ids;
 	struct ida in_hopids;

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