CVE-2021-47217

Name of the Vulnerable Software and Affected Versions Linux kernel versions prior to 5.15.0-rc2+

Description The vulnerability is related to a NULL pointer dereference in the set hv tscchange cb() function when setting Hyper-V's TSC change callback. If Hyper-V setup fails, the kernel will still report that it's running under Hyper-V, but will have silently disabled nearly all functionality. This can lead to a denial of service. The issue is caused by a kernel NULL pointer dereference, which occurs when the hv vp index array is not checked for validity before being dereferenced.

Recommendations To resolve the issue, update the Linux kernel to a version that includes the fix for the NULL pointer dereference in set hv tscchange cb(). As a temporary workaround, consider disabling the set hv tscchange cb() function until a patch is available. However, this may have unintended consequences and should be done with caution. At the moment, there is no information about a newer version that contains a fix for this vulnerability.