CVE-2023-53421

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> blk-cgroup: Reinit blkg_iostat_set after clearing in blkcg_reset_stats()<br /> <br /> When blkg_alloc() is called to allocate a blkcg_gq structure<br /> with the associated blkg_iostat_set&amp;#39;s, there are 2 fields within<br /> blkg_iostat_set that requires proper initialization - blkg &amp; sync.<br /> The former field was introduced by commit 3b8cc6298724 ("blk-cgroup:<br /> Optimize blkcg_rstat_flush()") while the later one was introduced by<br /> commit f73316482977 ("blk-cgroup: reimplement basic IO stats using<br /> cgroup rstat").<br /> <br /> Unfortunately those fields in the blkg_iostat_set&amp;#39;s are not properly<br /> re-initialized when they are cleared in v1&amp;#39;s blkcg_reset_stats(). This<br /> can lead to a kernel panic due to NULL pointer access of the blkg<br /> pointer. The missing initialization of sync is less problematic and<br /> can be a problem in a debug kernel due to missing lockdep initialization.<br /> <br /> Fix these problems by re-initializing them after memory clearing.