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CVE-2021-47318

arch_topology: Avoid use-after-free for scale_freq_data PUBLISHED

Description (CNA)

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.

Affected (CNA)

Vendor / productVersions
Linux / Linuxaffected 01e055c120a46e78650b5f903088badbbdaae9ad before ccdf7e073170886bc370c613e269de610a794c4a; affected 01e055c120a46e78650b5f903088badbbdaae9ad before 83150f5d05f065fb5c12c612f119015cabdcc124
Linux / Linuxaffected 5.13; unaffected 0 before 5.13; unaffected 5.13.4 through 5.13.*; unaffected 5.14 through *

CWE

No CWE identifiers supplied.

References

ADP enrichment

CVE

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CISA-ADP

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