| 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-2022-49655: fscache: Fix invalidation/lookup race |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| fscache: Fix invalidation/lookup race |
| |
| If an NFS file is opened for writing and closed, fscache_invalidate() will |
| be asked to invalidate the file - however, if the cookie is in the |
| LOOKING_UP state (or the CREATING state), then request to invalidate |
| doesn't get recorded for fscache_cookie_state_machine() to do something |
| with. |
| |
| Fix this by making __fscache_invalidate() set a flag if it sees the cookie |
| is in the LOOKING_UP state to indicate that we need to go to invalidation. |
| Note that this requires a count on the n_accesses counter for the state |
| machine, which that will release when it's done. |
| |
| fscache_cookie_state_machine() then shifts to the INVALIDATING state if it |
| sees the flag. |
| |
| Without this, an nfs file can get corrupted if it gets modified locally and |
| then read locally as the cache contents may not get updated. |
| |
| The Linux kernel CVE team has assigned CVE-2022-49655 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.17 with commit d24af13e2e2358a602740c7817ea90da43d3e740 and fixed in 5.18.11 with commit b1ae9f617f8a5c848d9205b8e228c6f0d1af754b |
| Issue introduced in 5.17 with commit d24af13e2e2358a602740c7817ea90da43d3e740 and fixed in 5.19 with commit 85e4ea1049c70fb99de5c6057e835d151fb647da |
| |
| 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-2022-49655 |
| 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/linux/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/b1ae9f617f8a5c848d9205b8e228c6f0d1af754b |
| https://git.kernel.org/stable/c/85e4ea1049c70fb99de5c6057e835d151fb647da |
