5.15-stable review patch. If anyone has any objections, please let me know.
------------------
From: Adrian Hunter <adrian.hunter@intel.com>
commit d2c743efd2d1ee64e94324664808f623dd865872 upstream.
i3c_master_unregister_i3c_devs() clears i3cdev->dev->desc before
calling device_unregister(). During device_unregister(),
device_del() emits a KOBJ_REMOVE uevent and unbinds the driver while
the device descriptor is still expected to be valid. As a result,
i3c_device_uevent() and a racing modalias_show() can observe a NULL
desc and fall back to an uninitialized stack struct i3c_device_info,
leaking kernel stack contents in the generated modalias. Driver
.remove() callbacks may also encounter an unexpected NULL desc during
unbind.
Keep desc valid until device_unregister() has completed. Since
device_unregister() drops the device reference and may free the device,
take an extra reference with get_device() before unregistering. Clear
desc afterwards and release the extra reference with put_device().
This preserves the release-time invariant that desc must be NULL while
avoiding both the information leak and a potential use-after-free from
writing desc after the device has been released.
Reported-by: sashiko-bot@kernel.org
Link: https://lore.kernel.org/linux-i3c/20260702190003.8BF741F000E9@smtp.kernel.org/ (local)
Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure")
Cc: <redacted>
Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Reviewed-by: Frank Li <Frank.Li@nxp.com>
Link: https://patch.msgid.link/20260723075747.34049-1-adrian.hunter@intel.com (local)
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/i3c/master.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)
--- a/drivers/i3c/master.c
+++ b/drivers/i3c/master.c
@@ -2237,11 +2237,12 @@ static void i3c_master_unregister_i3c_de
if (!i3cdev->dev)
continue;
- i3cdev->dev->desc = NULL;
- if (device_is_registered(&i3cdev->dev->dev))
+ if (device_is_registered(&i3cdev->dev->dev)) {
+ get_device(&i3cdev->dev->dev);
device_unregister(&i3cdev->dev->dev);
- else
- put_device(&i3cdev->dev->dev);
+ }
+ i3cdev->dev->desc = NULL;
+ put_device(&i3cdev->dev->dev);
i3cdev->dev = NULL;
}
}