CVE-2026-53187

Summary

In the Linux kernel, the following vulnerability has been resolved:

RDMA/core: Validate cpu_id against nr_cpu_ids in DMAH alloc

The cpu_id attribute supplied by user space through UVERBS_ATTR_ALLOC_DMAH_CPU_ID is passed directly to cpumask_test_cpu() without first verifying that the value is within the valid CPU range.

Passing such untrusted data to cpumask_test_cpu() may lead to an out-of-bounds read of the underlying cpumask bitmap: the helper expands to a test_bit() that indexes the bitmap by cpu_id / BITS_PER_LONG with no bound check.

In addition, on kernels built with CONFIG_DEBUG_PER_CPU_MAPS it trips the WARN_ON_ONCE() in cpumask_check(); combined with panic_on_warn this turns a bad user input into a machine reboot.

Reject any cpu_id that is not smaller than nr_cpu_ids with -EINVAL before it is used.

Reported by Smatch.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/bd5e818be7964c1689fba2dad9e6bd3a827fee74
• https://git.kernel.org/stable/c/0efbb6b54ff56300867027d8e0800d0e32226a20
• https://git.kernel.org/stable/c/323c98a4ff06aa28114f2bf658fb43eb3b536bbc

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