CVE-2023-53421

/// Technical description

In the Linux kernel, the following vulnerability has been resolved:

blk-cgroup: Reinit blkg_iostat_set after clearing in blkcg_reset_stats()

When blkg_alloc() is called to allocate a blkcg_gq structure

with the associated blkg_iostat_set's, there are 2 fields within

blkg_iostat_set that requires proper initialization - blkg & sync.

The former field was introduced by commit 3b8cc6298724 ("blk-cgroup:

Optimize blkcg_rstat_flush()") while the later one was introduced by

commit f73316482977 ("blk-cgroup: reimplement basic IO stats using

cgroup rstat").

Unfortunately those fields in the blkg_iostat_set's are not properly

re-initialized when they are cleared in v1's blkcg_reset_stats(). This

can lead to a kernel panic due to NULL pointer access of the blkg

pointer. The missing initialization of sync is less problematic and

can be a problem in a debug kernel due to missing lockdep initialization.

Fix these problems by re-initializing them after memory clearing.

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References