CVE-2025-39711

In the Linux kernel, the following vulnerability has been resolved:

media: ivsc: Fix crash at shutdown due to missing mei_cldev_disable() calls

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] … [ 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.

Weakness

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory “belongs” to the code that operates on the new pointer.

Affected Software

Potential Mitigations

References

• https://git.kernel.org/stable/c/0c92c49fc688cfadacc47ae99b06a31237702e9e
• https://git.kernel.org/stable/c/1dfe73394dcfc9b049c8da0dc181c45f156a5f49
• https://git.kernel.org/stable/c/3c0e4cc4f55f9a1db2a761e4ffb27c9594245888
• https://git.kernel.org/stable/c/639f5b33fcd7c59157f29b09f6f2866eacf9279c