CVE-2023-53052

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

cifs: fix use-after-free bug in refresh_cache_worker()

The UAF bug occurred because we were putting DFS root sessions in

cifs_umount() while DFS cache refresher was being executed.

Make DFS root sessions have same lifetime as DFS tcons so we can avoid

the use-after-free bug is DFS cache refresher and other places that

require IPCs to get new DFS referrals on. Also, get rid of mount

group handling in DFS cache as we no longer need it.

This fixes below use-after-free bug catched by KASAN

[ 379.946955] BUG: KASAN: use-after-free in __refresh_tcon.isra.0+0x10b/0xc10 [cifs]

[ 379.947642] Read of size 8 at addr ffff888018f57030 by task kworker/u4:3/56

[ 379.948096]

[ 379.948208] CPU: 0 PID: 56 Comm: kworker/u4:3 Not tainted 6.2.0-rc7-lku #23

[ 379.948661] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS

rel-1.16.0-0-gd239552-rebuilt.opensuse.org 04/01/2014

[ 379.949368] Workqueue: cifs-dfscache refresh_cache_worker [cifs]

[ 379.949942] Call Trace:

[ 379.950113] <TASK>

[ 379.950260] dump_stack_lvl+0x50/0x67

[ 379.950510] print_report+0x16a/0x48e

[ 379.950759] ? __virt_addr_valid+0xd8/0x160

[ 379.951040] ? __phys_addr+0x41/0x80

[ 379.951285] kasan_report+0xdb/0x110

[ 379.951533] ? __refresh_tcon.isra.0+0x10b/0xc10 [cifs]

[ 379.952056] ? __refresh_tcon.isra.0+0x10b/0xc10 [cifs]

[ 379.952585] __refresh_tcon.isra.0+0x10b/0xc10 [cifs]

[ 379.953096] ? __pfx___refresh_tcon.isra.0+0x10/0x10 [cifs]

[ 379.953637] ? __pfx___mutex_lock+0x10/0x10

[ 379.953915] ? lock_release+0xb6/0x720

[ 379.954167] ? __pfx_lock_acquire+0x10/0x10

[ 379.954443] ? refresh_cache_worker+0x34e/0x6d0 [cifs]

[ 379.954960] ? __pfx_wb_workfn+0x10/0x10

[ 379.955239] refresh_cache_worker+0x4ad/0x6d0 [cifs]

[ 379.955755] ? __pfx_refresh_cache_worker+0x10/0x10 [cifs]

[ 379.956323] ? __pfx_lock_acquired+0x10/0x10

[ 379.956615] ? read_word_at_a_time+0xe/0x20

[ 379.956898] ? lockdep_hardirqs_on_prepare+0x12/0x220

[ 379.957235] process_one_work+0x535/0x990

[ 379.957509] ? __pfx_process_one_work+0x10/0x10

[ 379.957812] ? lock_acquired+0xb7/0x5f0

[ 379.958069] ? __list_add_valid+0x37/0xd0

[ 379.958341] ? __list_add_valid+0x37/0xd0

[ 379.958611] worker_thread+0x8e/0x630

[ 379.958861] ? __pfx_worker_thread+0x10/0x10

[ 379.959148] kthread+0x17d/0x1b0

[ 379.959369] ? __pfx_kthread+0x10/0x10

[ 379.959630] ret_from_fork+0x2c/0x50

[ 379.959879] </TASK>