Attacker Value
Unknown
(0 users assessed)
Exploitability
Unknown
(0 users assessed)
User Interaction
None
Privileges Required
Low
Attack Vector
Local
0

CVE-2024-41058

Disclosure Date: July 29, 2024 •
CVE-2024-41058 CVSS v3 Base Score: 7.8
Add MITRE ATT&CK tactics and techniques that apply to this CVE.

Description

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

cachefiles: fix slab-use-after-free in fscache_withdraw_volume()

We got the following issue in our fault injection stress test:

==================================================================
BUG: KASAN: slab-use-after-free in fscache_withdraw_volume+0x2e1/0x370
Read of size 4 at addr ffff88810680be08 by task ondemand-04-dae/5798

CPU: 0 PID: 5798 Comm: ondemand-04-dae Not tainted 6.8.0-dirty #565
Call Trace:
kasan_check_range+0xf6/0x1b0
fscache_withdraw_volume+0x2e1/0x370
cachefiles_withdraw_volume+0x31/0x50
cachefiles_withdraw_cache+0x3ad/0x900
cachefiles_put_unbind_pincount+0x1f6/0x250
cachefiles_daemon_release+0x13b/0x290
__fput+0x204/0xa00
task_work_run+0x139/0x230

Allocated by task 5820:
__kmalloc+0x1df/0x4b0
fscache_alloc_volume+0x70/0x600
__fscache_acquire_volume+0x1c/0x610
erofs_fscache_register_volume+0x96/0x1a0
erofs_fscache_register_fs+0x49a/0x690
erofs_fc_fill_super+0x6c0/0xcc0
vfs_get_super+0xa9/0x140
vfs_get_tree+0x8e/0x300
do_new_mount+0x28c/0x580
[…]

Freed by task 5820:
kfree+0xf1/0x2c0
fscache_put_volume.part.0+0x5cb/0x9e0
erofs_fscache_unregister_fs+0x157/0x1b0
erofs_kill_sb+0xd9/0x1c0
deactivate_locked_super+0xa3/0x100
vfs_get_super+0x105/0x140
vfs_get_tree+0x8e/0x300
do_new_mount+0x28c/0x580

[…]

Following is the process that triggers the issue:

    mount failed         |         daemon exit

deactivate_locked_super cachefiles_daemon_release
erofs_kill_sb
erofs_fscache_unregister_fs

fscache_relinquish_volume
 __fscache_relinquish_volume
  fscache_put_volume(fscache_volume, fscache_volume_put_relinquish)
   zero = __refcount_dec_and_test(&fscache_volume->ref, &ref);
                             cachefiles_put_unbind_pincount
                              cachefiles_daemon_unbind
                               cachefiles_withdraw_cache
                                cachefiles_withdraw_volumes
                                 list_del_init(&volume->cache_link)
   fscache_free_volume(fscache_volume)
    cache->ops->free_volume
     cachefiles_free_volume
      list_del_init(&cachefiles_volume->cache_link);
    kfree(fscache_volume)
                                 cachefiles_withdraw_volume
                                  fscache_withdraw_volume
                                   fscache_volume->n_accesses
                                   // fscache_volume UAF !!!

The fscache_volume in cache->volumes must not have been freed yet, but its
reference count may be 0. So use the new fscache_try_get_volume() helper
function try to get its reference count.

If the reference count of fscache_volume is 0, fscache_put_volume() is
freeing it, so wait for it to be removed from cache->volumes.

If its reference count is not 0, call cachefiles_withdraw_volume() with
reference count protection to avoid the above issue.

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CVSS V3 Severity and Metrics
Base Score:
7.8 High
Impact Score:
5.9
Exploitability Score:
1.8
Vector:
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack Vector (AV):
Local
Attack Complexity (AC):
Low
Privileges Required (PR):
Low
User Interaction (UI):
None
Scope (S):
Unchanged
Confidentiality (C):
High
Integrity (I):
High
Availability (A):
High

General Information

Offensive Application
Unknown
Utility Class
Unknown
Ports
Unknown
OS
Unknown
Vulnerable Versions
Linux 90f17e47f1e2
Linux not down converted
Prerequisites
Unknown
Discovered By
Unknown
PoC Author
Unknown
Metasploit Module
Unknown
Reporter
Unknown

Vendors

  • linux

Products

  • linux kernel
Technical Analysis