FAILED: patch "[PATCH] i3c: master: Fix use-after-free of master->this" failed to apply to 5.15-stable tree

PATCH New [email protected] 2 participants 2 messages Sep 4 – Sep 10

Subsystems (2)

Stable branch I3C

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lore

[email protected]

author maintainer

2026-09-04 04:38 UTC #0 lore raw

The patch below does not apply to the 5.15-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-5.15.y
git checkout FETCH_HEAD
git cherry-pick -x feb0ed76601f3c2f91f08688c5a7d8b9d382f720
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '2026090432-surpass-exciting-1def@gregkh' --subject-prefix 'PATCH 5.15.y' 'HEAD^..'

Possible dependencies:

thanks,

greg k-h

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

From feb0ed76601f3c2f91f08688c5a7d8b9d382f720 Mon Sep 17 00:00:00 2001
From: Adrian Hunter <[email protected]>
Date: Fri, 7 Aug 2026 17:56:28 +0300
Subject: [PATCH] i3c: master: Fix use-after-free of master->this

sysfs attribute callbacks for the master controller device dereference master->this. However, master->this is freed in i3c_master_detach_free_devs() before the master device itself is released.

As a result, sysfs accesses can dereference a freed master->this pointer, leading to a use-after-free.

Keep master->this alive until i3c_masterdev_release(), which is called after the master device and its sysfs state are being torn down. Do not free master->this as part of the normal device detach path.

On the error path in i3c_master_set_info(), reset master->this and bus.cur_master to NULL before freeing the allocated device.

Fixes 3a379bbcea0a ("i3c: Add core I3C infrastructure")

Cc [email protected]

Signed-off-by Adrian Hunter <[email protected]>

Reviewed-by Frank Li <[email protected]>

Link https://patch.msgid.link/[email protected] open here

Signed-off-by Alexandre Belloni <[email protected]>

drivers/i3c/master.c +11 -6

index abb582645a2e..2357874bb9d6 100644
@@ -842,6 +842,11 @@ static struct attribute *i3c_masterdev_attrs[] = {
 };
 ATTRIBUTE_GROUPS(i3c_masterdev);
 
+static void i3c_master_free_i3c_dev(struct i3c_dev_desc *dev)
+{
+	kfree(dev);
+}
+
 static void i3c_masterdev_release(struct device *dev)
 {
 	struct i3c_master_controller *master = dev_to_i3cmaster(dev);

@@ -854,6 +859,8 @@ static void i3c_masterdev_release(struct device *dev)
 	i3c_bus_cleanup(bus);
 
 	fwnode_handle_put(dev->fwnode);
+
+	i3c_master_free_i3c_dev(master->this);
 }
 
 static const struct device_type i3c_masterdev_type = {

@@ -1125,11 +1132,6 @@ static void i3c_device_release(struct device *dev)
 	kfree(i3cdev);
 }
 
-static void i3c_master_free_i3c_dev(struct i3c_dev_desc *dev)
-{
-	kfree(dev);
-}
-
 static struct i3c_dev_desc *
 i3c_master_alloc_i3c_dev(struct i3c_master_controller *master,
 			 const struct i3c_device_info *info)

@@ -2266,6 +2268,8 @@ int i3c_master_set_info(struct i3c_master_controller *master,
 	return 0;
 
 err_free_dev:
+	master->bus.cur_master = NULL;
+	master->this = NULL;
 	i3c_master_free_i3c_dev(i3cdev);
 
 	return ret;

@@ -2286,7 +2290,8 @@ static void i3c_master_detach_free_devs(struct i3c_master_controller *master)
 					i3cdev->boardinfo->init_dyn_addr,
 					I3C_ADDR_SLOT_FREE);
 
-		i3c_master_free_i3c_dev(i3cdev);
+		if (i3cdev != master->this)
+			i3c_master_free_i3c_dev(i3cdev);
 	}
 
 	list_for_each_entry_safe(i2cdev, i2ctmp, &master->bus.devs.i2c,

Sasha Levin

maintainer

2026-09-10 01:26 UTC #1 lore raw

PATCH 1/1 i3c: master: Fix use-after-free of master->this

From: Adrian Hunter <[email protected]>

[ Upstream commit feb0ed76601f3c2f91f08688c5a7d8b9d382f720 ]