dax: Fix dax_mapping_release() use after free

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: dax: Fix dax_mapping_release() use after free A CONFIG_DEBUG_KOBJECT_RELEASE test of removing a device-dax region provider (like modprobe -r dax_hmem) yields: kobject: 'mapping0' (ffff93eb460e8800): kobject_release, parent 0000000000000000 (delayed 2000) [..] DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 23 PID: 282 at kernel/locking/lockdep.c:232 __lock_acquire+0x9fc/0x2260 [..] RIP: 0010:__lock_acquire+0x9fc/0x2260 [..] Call Trace: <TASK> [..] lock_acquire+0xd4/0x2c0 ? ida_free+0x62/0x130 _raw_spin_lock_irqsave+0x47/0x70 ? ida_free+0x62/0x130 ida_free+0x62/0x130 dax_mapping_release+0x1f/0x30 device_release+0x36/0x90 kobject_delayed_cleanup+0x46/0x150 Due to attempting ida_free() 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 dax_mapping to pin its parent dev_dax instance until dax_mapping_release().

References

• https://git.kernel.org/stable/c/94a85474f5e3e518bdbf8c9f51cb343d734a04f7
• https://git.kernel.org/stable/c/9c2f993b6ca903c030d58451b5bf9ea27d0d17fa
• https://git.kernel.org/stable/c/03859868ab82d57bfdd0cea1bf31f9319a5dded0
• https://git.kernel.org/stable/c/f76db6781d76d8464ec2faa9752cc3fb2e4f6923
• https://git.kernel.org/stable/c/7310b84821f043dcf77d5e6aa0ad55dc1e10a11d
• https://git.kernel.org/stable/c/6d24b170a9db0456f577b1ab01226a2254c016a8