| 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-2022-48989: fscache: Fix oops due to race with cookie_lru and use_cookie |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| fscache: Fix oops due to race with cookie_lru and use_cookie |
| |
| If a cookie expires from the LRU and the LRU_DISCARD flag is set, but |
| the state machine has not run yet, it's possible another thread can call |
| fscache_use_cookie and begin to use it. |
| |
| When the cookie_worker finally runs, it will see the LRU_DISCARD flag |
| set, transition the cookie->state to LRU_DISCARDING, which will then |
| withdraw the cookie. Once the cookie is withdrawn the object is removed |
| the below oops will occur because the object associated with the cookie |
| is now NULL. |
| |
| Fix the oops by clearing the LRU_DISCARD bit if another thread uses the |
| cookie before the cookie_worker runs. |
| |
| BUG: kernel NULL pointer dereference, address: 0000000000000008 |
| ... |
| CPU: 31 PID: 44773 Comm: kworker/u130:1 Tainted: G E 6.0.0-5.dneg.x86_64 #1 |
| Hardware name: Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022 |
| Workqueue: events_unbound netfs_rreq_write_to_cache_work [netfs] |
| RIP: 0010:cachefiles_prepare_write+0x28/0x90 [cachefiles] |
| ... |
| Call Trace: |
| netfs_rreq_write_to_cache_work+0x11c/0x320 [netfs] |
| process_one_work+0x217/0x3e0 |
| worker_thread+0x4a/0x3b0 |
| kthread+0xd6/0x100 |
| |
| The Linux kernel CVE team has assigned CVE-2022-48989 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.17 with commit 12bb21a29c19aae50cfad4e2bb5c943108f34a7d and fixed in 6.0.13 with commit 37f0b459c9b67e14fe4dcc3a15d286c4436ed01d |
| Issue introduced in 5.17 with commit 12bb21a29c19aae50cfad4e2bb5c943108f34a7d and fixed in 6.1 with commit b5b52de3214a29911f949459a79f6640969b5487 |
| |
| 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-2022-48989 |
| 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/fscache/cookie.c |
| include/trace/events/fscache.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/37f0b459c9b67e14fe4dcc3a15d286c4436ed01d |
| https://git.kernel.org/stable/c/b5b52de3214a29911f949459a79f6640969b5487 |
