| From bippy-5f407fcff5a0 Mon Sep 17 00:00:00 2001 |
| From: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| To: <linux-cve-announce@vger.kernel.org> |
| Reply-to: <cve@kernel.org>, <linux-kernel@vger.kernel.org> |
| Subject: CVE-2024-39510: cachefiles: fix slab-use-after-free in cachefiles_ondemand_daemon_read() |
| |
| Description |
| =========== |
| |
| 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. |
| |
| The Linux kernel CVE team has assigned CVE-2024-39510 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.8 with commit 0a7e54c1959c0feb2de23397ec09c7692364313e and fixed in 6.9.6 with commit 93064676a2820420a2d37d7c8289f277fe20793d |
| Issue introduced in 6.8 with commit 0a7e54c1959c0feb2de23397ec09c7692364313e and fixed in 6.10 with commit da4a827416066191aafeeccee50a8836a826ba10 |
| |
| Please see https://www.kernel.org for a full list of currently supported |
| kernel versions by the kernel community. |
| |
| Unaffected versions might change over time as fixes are backported to |
| older supported kernel versions. The official CVE entry at |
| https://cve.org/CVERecord/?id=CVE-2024-39510 |
| will be updated if fixes are backported, please check that for the most |
| up to date information about this issue. |
| |
| |
| Affected files |
| ============== |
| |
| The file(s) affected by this issue are: |
| fs/cachefiles/ondemand.c |
| include/trace/events/cachefiles.h |
| |
| |
| Mitigation |
| ========== |
| |
| The Linux kernel CVE team recommends that you update to the latest |
| stable kernel version for this, and many other bugfixes. Individual |
| changes are never tested alone, but rather are part of a larger kernel |
| release. Cherry-picking individual commits is not recommended or |
| supported by the Linux kernel community at all. If however, updating to |
| the latest release is impossible, the individual changes to resolve this |
| issue can be found at these commits: |
| https://git.kernel.org/stable/c/cb55625f8eb9d2de8be4da0c4580d48cbb32058e |
| https://git.kernel.org/stable/c/3958679c49152391209b32be3357193300a51abd |
| https://git.kernel.org/stable/c/93064676a2820420a2d37d7c8289f277fe20793d |
| https://git.kernel.org/stable/c/da4a827416066191aafeeccee50a8836a826ba10 |
