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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>
This commit is contained in:
Russell King 2009-09-28 11:41:51 +01:00
parent 90140c30a7
commit aa45ee8fc0
1 changed files with 4 additions and 1 deletions
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5
arch/arm/kernel/traps.c
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@ -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);
}
/*