From d2c743efd2d1ee64e94324664808f623dd865872 Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Thu, 23 Jul 2026 10:57:47 +0300 Subject: [PATCH] i3c: master: Fix info leak and UAF in device unregister path 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/ Fixes: 3a379bbcea0a ("i3c: Add core I3C infrastructure") Cc: stable@vger.kernel.org Signed-off-by: Adrian Hunter Reviewed-by: Frank Li Link: https://patch.msgid.link/20260723075747.34049-1-adrian.hunter@intel.com Signed-off-by: Alexandre Belloni --- drivers/i3c/master.c | 9 +++++---- 1 file changed, 5 insertions(+), 4 deletions(-) diff --git a/drivers/i3c/master.c b/drivers/i3c/master.c index fd3e79d10c84..b66729c7c3ec 100644 --- a/drivers/i3c/master.c +++ b/drivers/i3c/master.c @@ -3048,11 +3048,12 @@ static void i3c_master_unregister_i3c_devs(struct i3c_master_controller *master) 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; } }