Benjamin LaHaise 5e9ae2e5da aio: fix use-after-free in aio_migratepage ...

Dmitry Vyukov managed to trigger a case where aio_migratepage can cause a
use-after-free during teardown of the aio ring buffer's mapping.  This turns
out to be caused by access to the ioctx's ring_pages via the migratepage
operation which was not being protected by any locks during ioctx freeing.
Use the address_space's private_lock to protect use and updates of the mapping's
private_data, and make ioctx teardown unlink the ioctx from the address space.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Tested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Benjamin LaHaise <bcrl@kvack.org>

2013-09-26 20:34:51 -04:00

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