| 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-2021-47192: scsi: core: sysfs: Fix hang when device state is set via sysfs |
| |
| Description |
| =========== |
| |
| In the Linux kernel, the following vulnerability has been resolved: |
| |
| scsi: core: sysfs: Fix hang when device state is set via sysfs |
| |
| This fixes a regression added with: |
| |
| commit f0f82e2476f6 ("scsi: core: Fix capacity set to zero after |
| offlinining device") |
| |
| The problem is that after iSCSI recovery, iscsid will call into the kernel |
| to set the dev's state to running, and with that patch we now call |
| scsi_rescan_device() with the state_mutex held. If the SCSI error handler |
| thread is just starting to test the device in scsi_send_eh_cmnd() then it's |
| going to try to grab the state_mutex. |
| |
| We are then stuck, because when scsi_rescan_device() tries to send its I/O |
| scsi_queue_rq() calls -> scsi_host_queue_ready() -> scsi_host_in_recovery() |
| which will return true (the host state is still in recovery) and I/O will |
| just be requeued. scsi_send_eh_cmnd() will then never be able to grab the |
| state_mutex to finish error handling. |
| |
| To prevent the deadlock move the rescan-related code to after we drop the |
| state_mutex. |
| |
| This also adds a check for if we are already in the running state. This |
| prevents extra scans and helps the iscsid case where if the transport class |
| has already onlined the device during its recovery process then we don't |
| need userspace to do it again plus possibly block that daemon. |
| |
| The Linux kernel CVE team has assigned CVE-2021-47192 to this issue. |
| |
| |
| Affected and fixed versions |
| =========================== |
| |
| Issue introduced in 5.4.143 with commit 69aa1a1a569f5c6d554b59352130ef363342ed4c and fixed in 5.4.162 with commit edd783162bf2385b43de6764f2d4c6e9f4f6be27 |
| Issue introduced in 5.10.61 with commit 711459514e297d748f15ba1f5292a3276c3d1dd0 and fixed in 5.10.82 with commit a792e0128d232251edb5fdf42fb0f9fbb0b44a73 |
| Issue introduced in 5.14 with commit f0f82e2476f6adb9c7a0135cfab8091456990c99 and fixed in 5.15.5 with commit bcc0e3175a976b7fa9a353960808adb0bb49ead8 |
| Issue introduced in 5.14 with commit f0f82e2476f6adb9c7a0135cfab8091456990c99 and fixed in 5.16 with commit 4edd8cd4e86dd3047e5294bbefcc0a08f66a430f |
| Issue introduced in 5.13.13 with commit c6751ce1a2a415a78e4f5b621628da03196b804c |
| |
| 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-2021-47192 |
| 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: |
| drivers/scsi/scsi_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/edd783162bf2385b43de6764f2d4c6e9f4f6be27 |
| https://git.kernel.org/stable/c/a792e0128d232251edb5fdf42fb0f9fbb0b44a73 |
| https://git.kernel.org/stable/c/bcc0e3175a976b7fa9a353960808adb0bb49ead8 |
| https://git.kernel.org/stable/c/4edd8cd4e86dd3047e5294bbefcc0a08f66a430f |
