| 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-2024-57941: netfs: Fix the (non-)cancellation of copy when cache is temporarily disabled |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| netfs: Fix the (non-)cancellation of copy when cache is temporarily disabled |
| |
| When the caching for a cookie is temporarily disabled (e.g. due to a DIO |
| write on that file), future copying to the cache for that file is disabled |
| until all fds open on that file are closed. However, if netfslib is using |
| the deprecated PG_private_2 method (such as is currently used by ceph), and |
| decides it wants to copy to the cache, netfs_advance_write() will just bail |
| at the first check seeing that the cache stream is unavailable, and |
| indicate that it dealt with all the content. |
| |
| This means that we have no subrequests to provide notifications to drive |
| the state machine or even to pin the request and the request just gets |
| discarded, leaving the folios with PG_private_2 set. |
| |
| Fix this by jumping directly to cancel the request if the cache is not |
| available. That way, we don't remove mark3 from the folio_queue list and |
| netfs_pgpriv2_cancel() will clean up the folios. |
| |
| This was found by running the generic/013 xfstest against ceph with an |
| active cache and the "-o fsc" option passed to ceph. That would usually |
| hang |
| |
| The Linux kernel CVE team has assigned CVE-2024-57941 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.12 with commit ee4cdf7ba857a894ad1650d6ab77669cbbfa329e and fixed in 6.12.10 with commit ba37bdfe59fb43e80dd79290340a21864ba4b61e |
| Issue introduced in 6.12 with commit ee4cdf7ba857a894ad1650d6ab77669cbbfa329e and fixed in 6.13 with commit d0327c824338cdccad058723a31d038ecd553409 |
| |
| 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-2024-57941 |
| 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/netfs/read_pgpriv2.c |
| |
| |
| 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/ba37bdfe59fb43e80dd79290340a21864ba4b61e |
| https://git.kernel.org/stable/c/d0327c824338cdccad058723a31d038ecd553409 |
