Bug 2516633 (CVE-2026-72181)

Summary: CVE-2026-72181 kernel: mips: sched: Fix CPUMASK_OFFSTACK memory corruption
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's scheduler component, specifically when handling CPU masks on MIPS architecture with CONFIG_CPUMASK_OFFSTACK enabled. An incorrect size calculation during the copy_from_user() operation could lead to memory corruption. This vulnerability allows a local attacker to potentially overwrite kernel memory, which could result in a denial of service or privilege escalation.
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Description OSIDB Bzimport 2026-08-15 06:23:02 UTC 
In the Linux kernel, the following vulnerability has been resolved:

mips: sched: Fix CPUMASK_OFFSTACK memory corruption

This patch addresses a critical memory management flaw. When
CONFIG_CPUMASK_OFFSTACK is enabled, cpumask_var_t is a pointer.
Consequently, sizeof(new_mask) evaluates to the pointer size, causing
copy_from_user() to clobber the mask pointer. Furthermore, the old
logic performed copy_from_user() before allocating the mask.

Fix this by allocating new_mask first. To handle variable-sized user
masks correctly, use cpumask_size() to truncate overly large user masks
or pad undersized masks with zeros before copying the data directly into
the allocated buffer.
Comment 1 Keith Grant 2026-08-18 14:30:52 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081540-CVE-2026-72181-78f4@gregkh/T