CVE-2023-53613

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

dax: Fix daxmappingrelease() use after free

A CONFIGDEBUGKOBJECTRELEASE test of removing a device-dax region provider (like modprobe -r daxhmem) yields:

kobject: 'mapping0' (ffff93eb460e8800): kobjectrelease, parent 0000000000000000 (delayed 2000) [..] DEBUGLOCKSWARNON(1) WARNING: CPU: 23 PID: 282 at kernel/locking/lockdep.c:232 __lock_acquire+0x9fc/0x2260 [..] RIP: 0010:__lockacquire+0x9fc/0x2260 [..] Call Trace: <TASK> [..] lockacquire+0xd4/0x2c0 ? idafree+0x62/0x130 rawspinlockirqsave+0x47/0x70 ? idafree+0x62/0x130 idafree+0x62/0x130 daxmappingrelease+0x1f/0x30 devicerelease+0x36/0x90 kobjectdelayedcleanup+0x46/0x150

Due to attempting idafree() on an ida object that has already been freed. Devices typically only hold a reference on their parent while registered. If a child needs a parent object to complete its release it needs to hold a reference that it drops from its release callback. Arrange for a daxmapping to pin its parent devdax instance until daxmapping_release().