| 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-2024-57924: fs: relax assertions on failure to encode file handles |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| fs: relax assertions on failure to encode file handles |
| |
| Encoding file handles is usually performed by a filesystem >encode_fh() |
| method that may fail for various reasons. |
| |
| The legacy users of exportfs_encode_fh(), namely, nfsd and |
| name_to_handle_at(2) syscall are ready to cope with the possibility |
| of failure to encode a file handle. |
| |
| There are a few other users of exportfs_encode_{fh,fid}() that |
| currently have a WARN_ON() assertion when ->encode_fh() fails. |
| Relax those assertions because they are wrong. |
| |
| The second linked bug report states commit 16aac5ad1fa9 ("ovl: support |
| encoding non-decodable file handles") in v6.6 as the regressing commit, |
| but this is not accurate. |
| |
| The aforementioned commit only increases the chances of the assertion |
| and allows triggering the assertion with the reproducer using overlayfs, |
| inotify and drop_caches. |
| |
| Triggering this assertion was always possible with other filesystems and |
| other reasons of ->encode_fh() failures and more particularly, it was |
| also possible with the exact same reproducer using overlayfs that is |
| mounted with options index=on,nfs_export=on also on kernels < v6.6. |
| Therefore, I am not listing the aforementioned commit as a Fixes commit. |
| |
| Backport hint: this patch will have a trivial conflict applying to |
| v6.6.y, and other trivial conflicts applying to stable kernels < v6.6. |
| |
| The Linux kernel CVE team has assigned CVE-2024-57924 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Fixed in 6.6.74 with commit f47c834a9131ae64bee3c462f4e610c67b0a000f |
| Fixed in 6.12.10 with commit adcde2872f8fc399b249758ae1990dcd53b694ea |
| Fixed in 6.13 with commit 974e3fe0ac61de85015bbe5a4990cf4127b304b2 |
| |
| 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-2024-57924 |
| 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/notify/fdinfo.c |
| fs/overlayfs/copy_up.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/f47c834a9131ae64bee3c462f4e610c67b0a000f |
| https://git.kernel.org/stable/c/adcde2872f8fc399b249758ae1990dcd53b694ea |
| https://git.kernel.org/stable/c/974e3fe0ac61de85015bbe5a4990cf4127b304b2 |
