| 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-2024-40935: cachefiles: flush all requests after setting CACHEFILES_DEAD |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| cachefiles: flush all requests after setting CACHEFILES_DEAD |
| |
| In ondemand mode, when the daemon is processing an open request, if the |
| kernel flags the cache as CACHEFILES_DEAD, the cachefiles_daemon_write() |
| will always return -EIO, so the daemon can't pass the copen to the kernel. |
| Then the kernel process that is waiting for the copen triggers a hung_task. |
| |
| Since the DEAD state is irreversible, it can only be exited by closing |
| /dev/cachefiles. Therefore, after calling cachefiles_io_error() to mark |
| the cache as CACHEFILES_DEAD, if in ondemand mode, flush all requests to |
| avoid the above hungtask. We may still be able to read some of the cached |
| data before closing the fd of /dev/cachefiles. |
| |
| Note that this relies on the patch that adds reference counting to the req, |
| otherwise it may UAF. |
| |
| The Linux kernel CVE team has assigned CVE-2024-40935 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.19 with commit c8383054506c77b814489c09877b5db83fd4abf2 and fixed in 6.1.95 with commit 320ba9cbca78be79c912143bbba1d1b35ca55cf0 |
| Issue introduced in 5.19 with commit c8383054506c77b814489c09877b5db83fd4abf2 and fixed in 6.6.35 with commit 3bf0b8030296e9ee60d3d4c15849ad9ac0b47081 |
| Issue introduced in 5.19 with commit c8383054506c77b814489c09877b5db83fd4abf2 and fixed in 6.9.6 with commit e73fac95084839c5178d97e81c6a2051251bdc00 |
| Issue introduced in 5.19 with commit c8383054506c77b814489c09877b5db83fd4abf2 and fixed in 6.10 with commit 85e833cd7243bda7285492b0653c3abb1e2e757b |
| |
| 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-2024-40935 |
| 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/daemon.c |
| fs/cachefiles/internal.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/320ba9cbca78be79c912143bbba1d1b35ca55cf0 |
| https://git.kernel.org/stable/c/3bf0b8030296e9ee60d3d4c15849ad9ac0b47081 |
| https://git.kernel.org/stable/c/e73fac95084839c5178d97e81c6a2051251bdc00 |
| https://git.kernel.org/stable/c/85e833cd7243bda7285492b0653c3abb1e2e757b |
