| 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-2025-21807: block: fix queue freeze vs limits lock order in sysfs store methods |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| block: fix queue freeze vs limits lock order in sysfs store methods |
| |
| queue_attr_store() always freezes a device queue before calling the |
| attribute store operation. For attributes that control queue limits, the |
| store operation will also lock the queue limits with a call to |
| queue_limits_start_update(). However, some drivers (e.g. SCSI sd) may |
| need to issue commands to a device to obtain limit values from the |
| hardware with the queue limits locked. This creates a potential ABBA |
| deadlock situation if a user attempts to modify a limit (thus freezing |
| the device queue) while the device driver starts a revalidation of the |
| device queue limits. |
| |
| Avoid such deadlock by not freezing the queue before calling the |
| ->store_limit() method in struct queue_sysfs_entry and instead use the |
| queue_limits_commit_update_frozen helper to freeze the queue after taking |
| the limits lock. |
| |
| This also removes taking the sysfs lock for the store_limit method as |
| it doesn't protect anything here, but creates even more nesting. |
| Hopefully it will go away from the actual sysfs methods entirely soon. |
| |
| (commit log adapted from a similar patch from Damien Le Moal) |
| |
| The Linux kernel CVE team has assigned CVE-2025-21807 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.9 with commit 0327ca9d53bfbb0918867313049bba7046900f73 and fixed in 6.13.2 with commit 8985da5481562e96b95e94ed8e5cc9b6565eb82b |
| Issue introduced in 6.9 with commit 0327ca9d53bfbb0918867313049bba7046900f73 and fixed in 6.14 with commit c99f66e4084a62a2cc401c4704a84328aeddc9ec |
| |
| 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-2025-21807 |
| 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: |
| block/blk-sysfs.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/8985da5481562e96b95e94ed8e5cc9b6565eb82b |
| https://git.kernel.org/stable/c/c99f66e4084a62a2cc401c4704a84328aeddc9ec |
