CVE-2025-39711 in Linux
요약
\~에 의해 MITRE • 2025. 09. 05.
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] <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.
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