Commit 0dc294f7 authored Jan 30, 2015 by Arseny Solokha Committed by Scott Wood Jan 30, 2015

powerpc/mm: bail out early when flushing TLB page



MMU_NO_CONTEXT is conditionally defined as 0 or (unsigned int)-1. However,
in __flush_tlb_page() a corresponding variable is only tested for open
coded 0, which can cause NULL pointer dereference if `mm' argument was
legitimately passed as such.

Bail out early in case the first argument is NULL, thus eliminate confusion
between different values of MMU_NO_CONTEXT and avoid disabling and then
re-enabling preemption unnecessarily.

Signed-off-by: Arseny Solokha <asolokha@kb.kras.ru>
Signed-off-by: Scott Wood <scottwood@freescale.com>

parent c9111a41

arch/powerpc/mm/tlb_nohash.c

+4 −1

Original line number	Diff line number	Diff line
		@@ -284,8 +284,11 @@ void __flush_tlb_page(struct mm_struct *mm, unsigned long vmaddr,
		struct cpumask *cpu_mask;
		unsigned int pid;

		if (unlikely(!mm))
		return;

		preempt_disable();
		pid = mm ? mm->context.id : 0;
		pid = mm->context.id;
		if (unlikely(pid == MMU_NO_CONTEXT))
		goto bail;
		cpu_mask = mm_cpumask(mm);