CVE-2021-47192: scsi: core: sysfs: Fix hang when device state is set via sysfs
First published: Wed Apr 10 2024(Updated: )
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.
Credit: 416baaa9-dc9f-4396-8d5f-8c081fb06d67
| Affected Software | Affected Version | How to fix |
|---|---|---|
| Linux Kernel | ||
| Linux Kernel | >=5.4.143<5.4.162 | |
| Linux Kernel | >=5.10.61<5.10.82 | |
| Linux Kernel | >=5.13.13<5.15.5 | |
| Linux Kernel | =5.16-rc1 |
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Reference Links
Frequently Asked Questions
What is the severity of CVE-2021-47192?
CVE-2021-47192 has been classified as a low severity vulnerability affecting the Linux kernel.
How do I fix CVE-2021-47192?
Fixing CVE-2021-47192 involves updating the Linux kernel to a version that includes the patch for this vulnerability.
What impact does CVE-2021-47192 have on the Linux kernel?
CVE-2021-47192 can cause a hang when the device state is altered via sysfs, particularly after offlining a device.
Is CVE-2021-47192 present in all versions of the Linux kernel?
CVE-2021-47192 affects certain versions of the Linux kernel that include the problematic commit f0f82e2476f6.
Where can I find more information about CVE-2021-47192?
For more information about CVE-2021-47192, refer to the relevant section in the Linux kernel change logs.
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