7.8

CVE-2024-39510

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

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

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

We got the following issue in a fuzz test of randomly issuing the restore
command:

==================================================================
BUG: KASAN: slab-use-after-free in cachefiles_ondemand_daemon_read+0xb41/0xb60
Read of size 8 at addr ffff888122e84088 by task ondemand-04-dae/963

CPU: 13 PID: 963 Comm: ondemand-04-dae Not tainted 6.8.0-dirty #564
Call Trace:
 kasan_report+0x93/0xc0
 cachefiles_ondemand_daemon_read+0xb41/0xb60
 vfs_read+0x169/0xb50
 ksys_read+0xf5/0x1e0

Allocated by task 116:
 kmem_cache_alloc+0x140/0x3a0
 cachefiles_lookup_cookie+0x140/0xcd0
 fscache_cookie_state_machine+0x43c/0x1230
 [...]

Freed by task 792:
 kmem_cache_free+0xfe/0x390
 cachefiles_put_object+0x241/0x480
 fscache_cookie_state_machine+0x5c8/0x1230
 [...]
==================================================================

Following is the process that triggers the issue:

     mount  |   daemon_thread1    |    daemon_thread2
------------------------------------------------------------
cachefiles_withdraw_cookie
 cachefiles_ondemand_clean_object(object)
  cachefiles_ondemand_send_req
   REQ_A = kzalloc(sizeof(*req) + data_len)
   wait_for_completion(&REQ_A->done)

            cachefiles_daemon_read
             cachefiles_ondemand_daemon_read
              REQ_A = cachefiles_ondemand_select_req
              msg->object_id = req->object->ondemand->ondemand_id
                                  ------ restore ------
                                  cachefiles_ondemand_restore
                                  xas_for_each(&xas, req, ULONG_MAX)
                                   xas_set_mark(&xas, CACHEFILES_REQ_NEW)

                                  cachefiles_daemon_read
                                   cachefiles_ondemand_daemon_read
                                    REQ_A = cachefiles_ondemand_select_req
              copy_to_user(_buffer, msg, n)
               xa_erase(&cache->reqs, id)
               complete(&REQ_A->done)
              ------ close(fd) ------
              cachefiles_ondemand_fd_release
               cachefiles_put_object
 cachefiles_put_object
  kmem_cache_free(cachefiles_object_jar, object)
                                    REQ_A->object->ondemand->ondemand_id
                                     // object UAF !!!

When we see the request within xa_lock, req->object must not have been
freed yet, so grab the reference count of object before xa_unlock to
avoid the above issue.
Daten sind bereitgestellt durch National Vulnerability Database (NVD)
Linux ≫ Linux Kernel Version >= 6.8 < 6.9.6
Linux ≫ Linux Kernel Version6.10 Updaterc1
Linux ≫ Linux Kernel Version6.10 Updaterc2
Linux ≫ Linux Kernel Version6.10 Updaterc3
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Zu dieser CVE wurde keine Warnung gefunden.
EPSS Metriken
Typ Quelle Score Percentile
EPSS FIRST.org 0.28% 0.198
CVSS Metriken
Quelle Base Score Exploit Score Impact Score Vector String
nvd@nist.gov 7.8 1.8 5.9
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CWE-416 Use After Free

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory "belongs" to the code that operates on the new pointer.

https://git.kernel.org/stable/c/3958679c49152391209b32be3357193300a51abd
Patch
https://git.kernel.org/stable/c/93064676a2820420a2d37d7c8289f277fe20793d
Patch
https://git.kernel.org/stable/c/cb55625f8eb9d2de8be4da0c4580d48cbb32058e
Patch
https://git.kernel.org/stable/c/da4a827416066191aafeeccee50a8836a826ba10
Patch
https://lists.debian.org/debian-lts-announce/2025/01/msg00001.html