CVE-2025-71109

/// Technical description

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

MIPS: ftrace: Fix memory corruption when kernel is located beyond 32 bits

Since commit e424054000878 ("MIPS: Tracing: Reduce the overhead of

dynamic Function Tracer"), the macro UASM_i_LA_mostly has been used,

and this macro can generate more than 2 instructions. At the same

time, the code in ftrace assumes that no more than 2 instructions can

be generated, which is why it stores them in an int[2] array. However,

as previously noted, the macro UASM_i_LA_mostly (and now UASM_i_LA)

causes a buffer overflow when _mcount is beyond 32 bits. This leads to

corruption of the variables located in the __read_mostly section.

This corruption was observed because the variable

__cpu_primary_thread_mask was corrupted, causing a hang very early

during boot.

This fix prevents the corruption by avoiding the generation of

instructions if they could exceed 2 instructions in

length. Fortunately, insn_la_mcount is only used if the instr

/// Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

/// References