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Commit aa45ee8f authored by Russell King's avatar Russell King
Browse files

ARM: Ensure do_cache_op takes mmap_sem 



do_cache_op() uses find_vma() to validate its arguments without holding
any locking.  This means that the VMA could vanish beneath us.  Fix
this by taking a read lock on mmap_sem.

Signed-off-by: default avatarRussell King <rmk+kernel@arm.linux.org.uk>
parent 90140c30

arch/arm/kernel/traps.c

+4 −1
Original line number Diff line number Diff line
@@ -418,12 +418,14 @@ static int bad_syscall(int n, struct pt_regs *regs) 
static inline void

do_cache_op(unsigned long start, unsigned long end, int flags)

{

	struct mm_struct *mm = current->active_mm;

	struct vm_area_struct *vma;



	if (end < start || flags)

		return;



	vma = find_vma(current->active_mm, start);

	down_read(&mm->mmap_sem);

	vma = find_vma(mm, start);

	if (vma && vma->vm_start < end) {

		if (start < vma->vm_start)

			start = vma->vm_start;
@@ -432,6 +434,7 @@ do_cache_op(unsigned long start, unsigned long end, int flags) 


		flush_cache_user_range(vma, start, end);

	}

	up_read(&mm->mmap_sem);

}



/*