CVE-2026-93795blk-cgroup: fix leaks and online flag on radix_tree_insert failure

Official description

In the Linux kernel, the following vulnerability has been resolved: blk-cgroup: fix leaks and online flag on radix_tree_insert failure When radix_tree_insert() fails in blkg_create(), the error path has two issues: 1. blkg->online is set to true unconditionally, even when the blkg was never fully inserted. Move the assignment inside the success block. 2. The error path calls blkg_put() without first calling percpu_ref_kill(). Because the refcount is still in percpu mode, percpu_ref_put() only does this_cpu_sub() without checking for zero, so blkg_release() is never triggered. This permanently leaks the blkg memory, its percpu iostat, policy data, the parent blkg reference, and the cgroup css reference — the latter preventing the cgroup from ever being destroyed. Fix by replacing blkg_put() with percpu_ref_kill(), matching the pattern used in blkg_destroy().

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/0f840db042caee9d2f3dcdcf97d6674f6e4c1e30
• https://git.kernel.org/stable/c/f53945d7c712efe63fadbcc5ffed6370871fd0d3
• https://git.kernel.org/stable/c/ada8270ccdb6f212da5eb22614c28ea418746a4a
• https://git.kernel.org/stable/c/c3650be82ef6e7af13b79b2d10a7363bdf54aa7f
• https://git.kernel.org/stable/c/6e85f02d45b5977c0326a8d854c6db878aa6b34a
• https://git.kernel.org/stable/c/4c0d150fb98ea40760611979f4e664c244b20966
• https://git.kernel.org/stable/c/dbbca20764382b4d411ec2918f4e278ffe547acc