CVE-2026-93795

Summary

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 Software

VendorProductVersion RangeStatus
LinuxLinux7fcf2b033b84e261dca283bc2911aaea4b07b525 < 0f840db042caee9d2f3dcdcf97d6674f6e4c1e30affected
LinuxLinux7fcf2b033b84e261dca283bc2911aaea4b07b525 < f53945d7c712efe63fadbcc5ffed6370871fd0d3affected
LinuxLinux7fcf2b033b84e261dca283bc2911aaea4b07b525 < ada8270ccdb6f212da5eb22614c28ea418746a4aaffected
LinuxLinux7fcf2b033b84e261dca283bc2911aaea4b07b525 < c3650be82ef6e7af13b79b2d10a7363bdf54aa7faffected
LinuxLinux7fcf2b033b84e261dca283bc2911aaea4b07b525 < 6e85f02d45b5977c0326a8d854c6db878aa6b34aaffected
LinuxLinux7fcf2b033b84e261dca283bc2911aaea4b07b525 < 4c0d150fb98ea40760611979f4e664c244b20966affected
LinuxLinux7fcf2b033b84e261dca283bc2911aaea4b07b525 < dbbca20764382b4d411ec2918f4e278ffe547accaffected
LinuxLinux5.0affected
LinuxLinux0 < 5.0unaffected
LinuxLinux5.10.271 <= 5.10.*unaffected
LinuxLinux5.15.222 <= 5.15.*unaffected
LinuxLinux6.1.189 <= 6.1.*unaffected
LinuxLinux6.6.158 <= 6.6.*unaffected
LinuxLinux6.12.111 <= 6.12.*unaffected
LinuxLinux6.18.53 <= 6.18.*unaffected
LinuxLinux7.2 <= *unaffected

Weaknesses

References