6.6-stable review patch. If anyone has any objections, please let me know.
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From: Hans de Goede hansg@kernel.org
commit 0c92c49fc688cfadacc47ae99b06a31237702e9e upstream.
Both the ACE and CSI driver are missing a mei_cldev_disable() call in their remove() function.
This causes the mei_cl client to stay part of the mei_device->file_list list even though its memory is freed by mei_cl_bus_dev_release() calling kfree(cldev->cl).
This leads to a use-after-free when mei_vsc_remove() runs mei_stop() which first removes all mei bus devices calling mei_ace_remove() and mei_csi_remove() followed by mei_cl_bus_dev_release() and then calls mei_cl_all_disconnect() which walks over mei_device->file_list dereferecing the just freed cldev->cl.
And mei_vsc_remove() it self is run at shutdown because of the platform_device_unregister(tp->pdev) in vsc_tp_shutdown()
When building a kernel with KASAN this leads to the following KASAN report:
[ 106.634504] ================================================================== [ 106.634623] BUG: KASAN: slab-use-after-free in mei_cl_set_disconnected (drivers/misc/mei/client.c:783) mei [ 106.634683] Read of size 4 at addr ffff88819cb62018 by task systemd-shutdow/1 [ 106.634729] [ 106.634767] Tainted: [E]=UNSIGNED_MODULE [ 106.634770] Hardware name: Dell Inc. XPS 16 9640/09CK4V, BIOS 1.12.0 02/10/2025 [ 106.634773] Call Trace: [ 106.634777] <TASK> ... [ 106.634871] kasan_report (mm/kasan/report.c:221 mm/kasan/report.c:636) [ 106.634901] mei_cl_set_disconnected (drivers/misc/mei/client.c:783) mei [ 106.634921] mei_cl_all_disconnect (drivers/misc/mei/client.c:2165 (discriminator 4)) mei [ 106.634941] mei_reset (drivers/misc/mei/init.c:163) mei ... [ 106.635042] mei_stop (drivers/misc/mei/init.c:348) mei [ 106.635062] mei_vsc_remove (drivers/misc/mei/mei_dev.h:784 drivers/misc/mei/platform-vsc.c:393) mei_vsc [ 106.635066] platform_remove (drivers/base/platform.c:1424)
Add the missing mei_cldev_disable() calls so that the mei_cl gets removed from mei_device->file_list before it is freed to fix this.
Fixes: 78876f71b3e9 ("media: pci: intel: ivsc: Add ACE submodule") Fixes: 29006e196a56 ("media: pci: intel: ivsc: Add CSI submodule") Cc: stable@vger.kernel.org Signed-off-by: Hans de Goede hansg@kernel.org Signed-off-by: Sakari Ailus sakari.ailus@linux.intel.com Signed-off-by: Hans Verkuil hverkuil@xs4all.nl Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/media/pci/intel/ivsc/mei_ace.c | 2 ++ drivers/media/pci/intel/ivsc/mei_csi.c | 2 ++ 2 files changed, 4 insertions(+)
--- a/drivers/media/pci/intel/ivsc/mei_ace.c +++ b/drivers/media/pci/intel/ivsc/mei_ace.c @@ -528,6 +528,8 @@ static void mei_ace_remove(struct mei_cl
ace_set_camera_owner(ace, ACE_CAMERA_IVSC);
+ mei_cldev_disable(cldev); + mutex_destroy(&ace->lock); }
--- a/drivers/media/pci/intel/ivsc/mei_csi.c +++ b/drivers/media/pci/intel/ivsc/mei_csi.c @@ -807,6 +807,8 @@ static void mei_csi_remove(struct mei_cl
pm_runtime_disable(&cldev->dev);
+ mei_cldev_disable(cldev); + mutex_destroy(&csi->lock); }