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 UASMiLAmostly 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 UASMiLAmostly (and now UASMiLA) 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 _cpuprimarythreadmask 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, insnlamcount is only used if the instrumented code is located outside the kernel code section, so dynamic ftrace can still be used, albeit in a more limited scope. This is still preferable to corrupting memory and/or crashing the kernel.
{
"cna_assigner": "Linux",
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/71xxx/CVE-2025-71109.json"
}