Messages in this thread Patch in this message |  | | | Date | Wed, 16 Dec 2009 17:14:22 -0800 | | From | Greg KH <> | | Subject | [11/90] futex: Take mmap_sem for get_user_pages in fault_in_user_writeable |
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2.6.31-stable review patch. If anyone has any objections, please let us know.
------------------ From: Andi Kleen <andi@firstfloor.org>
commit 722d0172377a5697919b9f7e5beb95165b1dec4e upstream.
get_user_pages() must be called with mmap_sem held.
Signed-off-by: Andi Kleen <ak@linux.intel.com> 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> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- kernel/futex.c | 10 ++++++++-- 1 file changed, 8 insertions(+), 2 deletions(-) --- a/kernel/futex.c +++ b/kernel/futex.c @@ -303,8 +303,14 @@ void put_futex_key(int fshared, union fu */ 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; }
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