| 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-2024-26899: block: fix deadlock between bd_link_disk_holder and partition scan |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| block: fix deadlock between bd_link_disk_holder and partition scan |
| |
| 'open_mutex' of gendisk is used to protect open/close block devices. But |
| in bd_link_disk_holder(), it is used to protect the creation of symlink |
| between holding disk and slave bdev, which introduces some issues. |
| |
| When bd_link_disk_holder() is called, the driver is usually in the process |
| of initialization/modification and may suspend submitting io. At this |
| time, any io hold 'open_mutex', such as scanning partitions, can cause |
| deadlocks. For example, in raid: |
| |
| T1 T2 |
| bdev_open_by_dev |
| lock open_mutex [1] |
| ... |
| efi_partition |
| ... |
| md_submit_bio |
| md_ioctl mddev_syspend |
| -> suspend all io |
| md_add_new_disk |
| bind_rdev_to_array |
| bd_link_disk_holder |
| try lock open_mutex [2] |
| md_handle_request |
| -> wait mddev_resume |
| |
| T1 scan partition, T2 add a new device to raid. T1 waits for T2 to resume |
| mddev, but T2 waits for open_mutex held by T1. Deadlock occurs. |
| |
| Fix it by introducing a local mutex 'blk_holder_mutex' to replace |
| 'open_mutex'. |
| |
| The Linux kernel CVE team has assigned CVE-2024-26899 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 6.7 with commit 1b0a2d950ee2a54aa04fb31ead32144be0bbf690 and fixed in 6.7.11 with commit 1e5c5b0abaee7b62a10b9707a62083b71ad21f62 |
| Issue introduced in 6.7 with commit 1b0a2d950ee2a54aa04fb31ead32144be0bbf690 and fixed in 6.8.2 with commit 5a87c1f7993bc8ac358a3766bac5dc7126e01e98 |
| Issue introduced in 6.7 with commit 1b0a2d950ee2a54aa04fb31ead32144be0bbf690 and fixed in 6.9 with commit 03f12122b20b6e6028e9ed69030a49f9cffcbb75 |
| |
| 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-2024-26899 |
| 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/holder.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/1e5c5b0abaee7b62a10b9707a62083b71ad21f62 |
| https://git.kernel.org/stable/c/5a87c1f7993bc8ac358a3766bac5dc7126e01e98 |
| https://git.kernel.org/stable/c/03f12122b20b6e6028e9ed69030a49f9cffcbb75 |
