Bugzilla – Bug 1225057
VUL-0: CVE-2021-47318: kernel: arch_topology: avoid use-after-free for scale_freq_data
Last modified: 2024-07-08 09:48:56 UTC
In the Linux kernel, the following vulnerability has been resolved: arch_topology: Avoid use-after-free for scale_freq_data Currently topology_scale_freq_tick() (which gets called from scheduler_tick()) may end up using a pointer to "struct scale_freq_data", which was previously cleared by topology_clear_scale_freq_source(), as there is no protection in place here. The users of topology_clear_scale_freq_source() though needs a guarantee that the previously cleared scale_freq_data isn't used anymore, so they can free the related resources. Since topology_scale_freq_tick() is called from scheduler tick, we don't want to add locking in there. Use the RCU update mechanism instead (which is already used by the scheduler's utilization update path) to guarantee race free updates here. synchronize_rcu() makes sure that all RCU critical sections that started before it is called, will finish before it returns. And so the callers of topology_clear_scale_freq_source() don't need to worry about their callback getting called anymore. References: http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2021-47318 https://www.cve.org/CVERecord?id=CVE-2021-47318 https://git.kernel.org/stable/c/83150f5d05f065fb5c12c612f119015cabdcc124 https://git.kernel.org/stable/c/ccdf7e073170886bc370c613e269de610a794c4a https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2021/CVE-2021-47318.mbox
joeyli@linux-691t:/mnt/working/source_code-git/kernel-source> ./scripts/check-kernel-fix CVE-2021-47318 83150f5d05f0 ("arch_topology: Avoid use-after-free for scale_freq_data") merged v5.14-rc1~47^2~1^2^2~1 Fixes: 01e055c120a4 ("arch_topology: Allow multiple entities to provide sched_freq_tick() callback") merged v5.13-rc1~156^2~4^2~1^2~14 Security fix for CVE-2021-47318 bsc#1225057 with CVSS 7 Experts candidates: tiwai@suse.de .............................. NO ACTION NEEDED: All relevant branches contain the fix! This issue did not affect any kernel branch. reset assigner
All done, closing.