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Use After Free Affecting kernel-default-base package, versions <6.4.0-150600.23.22.1.150600.12.8.3

Severity

 Recommended
0.0
medium
0
10

Based on SUSE Linux Enterprise Server security rating.

Threat Intelligence

EPSS
0.04% (6th percentile)

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  • Snyk IDSNYK-SLES156-KERNELDEFAULTBASE-8075062
  • published24 Sept 2024
  • disclosed23 Sept 2024
Report a new vulnerability Found a mistake?

Introduced: 23 Sep 2024

CVE-2024-39510  (opens in a new tab)
CWE-416  (opens in a new tab)

How to fix?

Upgrade SLES:15.6 kernel-default-base to version 6.4.0-150600.23.22.1.150600.12.8.3 or higher.

NVD Description

Note: Versions mentioned in the description apply only to the upstream kernel-default-base package and not the kernel-default-base package as distributed by SLES. See How to fix? for SLES:15.6 relevant fixed versions and status.

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-&gt;object_id = req-&gt;object-&gt;ondemand-&gt;ondemand_id
                              ------ restore ------
                              cachefiles_ondemand_restore
                              xas_for_each(&amp;xas, req, ULONG_MAX)
                               xas_set_mark(&amp;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(&amp;amp;cache-&amp;gt;reqs, id)
       complete(&amp;amp;REQ_A-&amp;gt;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.

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