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futex: Take mmap_sem for get_user_pages in fault_in_user_writeable

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get_user_pages() must be called with mmap_sem held.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: stable@kernel.org
Cc: Andrew Morton <akpm@linuxfoundation.org>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Darren Hart <dvhltc@us.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <20091208121942.GA21298@basil.fritz.box>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Andi Kleen 2009-12-08 13:19:42 +01:00 committed by Thomas Gleixner
parent f5754bfd10
commit 722d017237
1 changed files with 8 additions and 2 deletions
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10
kernel/futex.c
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@ -304,8 +304,14 @@ void put_futex_key(int fshared, union futex_key *key)
*/
static int fault_in_user_writeable(u32 __user *uaddr)
{
int ret = get_user_pages(current, current->mm, (unsigned long)uaddr,
1, 1, 0, NULL, NULL);
struct mm_struct *mm = current->mm;
int ret;
down_read(&mm->mmap_sem);
ret = get_user_pages(current, mm, (unsigned long)uaddr,
1, 1, 0, NULL, NULL);
up_read(&mm->mmap_sem);
return ret < 0 ? ret : 0;
}