CVE-2021-47178

Name of the Vulnerable Software and Affected Versions Linux kernel versions prior to 5.13.0-rc1+ #34

Description A vulnerability has been resolved in the Linux kernel, specifically in the scsi: target: core, where the function smp processor id() was called in preemptible code, triggering a BUG message. This issue was observed when running blktests block/005 on TCMU devices with fileio backend or user:zbc backend, and also at system shutdown when TCMU devices were not cleaned up. The commit 1130b499b4a7 modified the work queue to handle commands and changed 'current->nr cpu allowed' at smp processor id() call, triggering the symptom. To avoid this issue, the CPU ID is now obtained with raw smp processor id() instead.

Recommendations To resolve this issue, update the Linux kernel to a version newer than 5.13.0-rc1+ #34. As a temporary workaround, consider disabling the smp processor id() function until a patch is available. However, since the issue is already resolved by using raw smp processor id() instead, updating the kernel should suffice.