提交 f6c4fd50 编写于 作者: T Thomas Gleixner

x86/cpu_entry_area: Prevent wraparound in setup_cpu_entry_area_ptes() on 32bit

The loop which populates the CPU entry area PMDs can wrap around on 32bit
machines when the number of CPUs is small.

It worked wonderful for NR_CPUS=64 for whatever reason and the moron who
wrote that code did not bother to test it with !SMP.

Check for the wraparound to fix it.

Fixes: 92a0f81d ("x86/cpu_entry_area: Move it out of the fixmap")
Reported-by: Nkernel test robot <fengguang.wu@intel.com>
Signed-off-by: NThomas "Feels stupid" Gleixner <tglx@linutronix.de>
Tested-by: NBorislav Petkov <bp@alien8.de>
上级 613e396b
......@@ -122,7 +122,8 @@ static __init void setup_cpu_entry_area_ptes(void)
start = CPU_ENTRY_AREA_BASE;
end = start + CPU_ENTRY_AREA_MAP_SIZE;
for (; start < end; start += PMD_SIZE)
/* Careful here: start + PMD_SIZE might wrap around */
for (; start < end && start >= CPU_ENTRY_AREA_BASE; start += PMD_SIZE)
populate_extra_pte(start);
#endif
}
......
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