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: Russell King <rmk+kernel@arm.linux.org.uk>
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@ -418,12 +418,14 @@ static int bad_syscall(int n, struct pt_regs *regs)
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static inline void
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static inline void
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do_cache_op(unsigned long start, unsigned long end, int flags)
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do_cache_op(unsigned long start, unsigned long end, int flags)
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{
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{
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struct mm_struct *mm = current->active_mm;
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struct vm_area_struct *vma;
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struct vm_area_struct *vma;
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if (end < start || flags)
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if (end < start || flags)
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return;
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return;
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vma = find_vma(current->active_mm, start);
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down_read(&mm->mmap_sem);
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vma = find_vma(mm, start);
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if (vma && vma->vm_start < end) {
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if (vma && vma->vm_start < end) {
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if (start < vma->vm_start)
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if (start < vma->vm_start)
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start = vma->vm_start;
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start = vma->vm_start;
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@ -432,6 +434,7 @@ do_cache_op(unsigned long start, unsigned long end, int flags)
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flush_cache_user_range(vma, start, end);
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flush_cache_user_range(vma, start, end);
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}
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}
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up_read(&mm->mmap_sem);
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}
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}
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/*
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/*
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