Commit 86331489 authored by Baokun Li's avatar Baokun Li Committed by Zhihao Cheng
Browse files

fscache: delete fscache_cookie_lru_timer when fscache exits to avoid UAF 

stable inclusion
from stable-v6.6.52
commit e0d724932ad12e3528f4ce97fc0f6078d0cce4bc
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IARWDH
CVE: CVE-2024-46786

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/fs/fscache?h=v6.6.52&id=e0d724932ad12e3528f4ce97fc0f6078d0cce4bc



--------------------------------

commit 72a6e22c604c95ddb3b10b5d3bb85b6ff4dbc34f upstream.

The fscache_cookie_lru_timer is initialized when the fscache module
is inserted, but is not deleted when the fscache module is removed.
If timer_reduce() is called before removing the fscache module,
the fscache_cookie_lru_timer will be added to the timer list of
the current cpu. Afterwards, a use-after-free will be triggered
in the softIRQ after removing the fscache module, as follows:

==================================================================
BUG: unable to handle page fault for address: fffffbfff803c9e9
 PF: supervisor read access in kernel mode
 PF: error_code(0x0000) - not-present page
PGD 21ffea067 P4D 21ffea067 PUD 21ffe6067 PMD 110a7c067 PTE 0
Oops: Oops: 0000 [#1] PREEMPT SMP KASAN PTI
CPU: 1 UID: 0 PID: 0 Comm: swapper/1 Tainted: G W 6.11.0-rc3 #855
Tainted: [W]=WARN
RIP: 0010:__run_timer_base.part.0+0x254/0x8a0
Call Trace:
 <IRQ>
 tmigr_handle_remote_up+0x627/0x810
 __walk_groups.isra.0+0x47/0x140
 tmigr_handle_remote+0x1fa/0x2f0
 handle_softirqs+0x180/0x590
 irq_exit_rcu+0x84/0xb0
 sysvec_apic_timer_interrupt+0x6e/0x90
 </IRQ>
 <TASK>
 asm_sysvec_apic_timer_interrupt+0x1a/0x20
RIP: 0010:default_idle+0xf/0x20
 default_idle_call+0x38/0x60
 do_idle+0x2b5/0x300
 cpu_startup_entry+0x54/0x60
 start_secondary+0x20d/0x280
 common_startup_64+0x13e/0x148
 </TASK>
Modules linked in: [last unloaded: netfs]
==================================================================

Therefore delete fscache_cookie_lru_timer when removing the fscahe module.

Fixes: 12bb21a2 ("fscache: Implement cookie user counting and resource pinning")
Cc: stable@kernel.org
Signed-off-by: default avatarBaokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240826112056.2458299-1-libaokun@huaweicloud.com


Acked-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarChristian Brauner <brauner@kernel.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: default avatarZhihao Cheng <chengzhihao1@huawei.com>
parent 70e304bd

fs/fscache/main.c

+1 −0
Original line number Diff line number Diff line
@@ -114,6 +114,7 @@ static void __exit fscache_exit(void) 


	kmem_cache_destroy(fscache_cookie_jar);

	fscache_proc_cleanup();

	timer_shutdown_sync(&fscache_cookie_lru_timer);

	destroy_workqueue(fscache_wq);

	pr_notice("Unloaded\n");

}