aio: check for multiplication overflow in do_io_submit
authorJeff Moyer <jmoyer@redhat.com>
Fri, 10 Sep 2010 21:16:00 +0000 (14:16 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 15 Sep 2010 00:02:37 +0000 (17:02 -0700)
commit75e1c70fc31490ef8a373ea2a4bea2524099b478
tree4fc943276b4a34374ac26d69e63b815bf66c2451
parentbfa88ea7ee9e6b4fd673e45a8cc0a8e0b7ef4761
aio: check for multiplication overflow in do_io_submit

Tavis Ormandy pointed out that do_io_submit does not do proper bounds
checking on the passed-in iocb array:

       if (unlikely(nr < 0))
               return -EINVAL;

       if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(iocbpp)))))
               return -EFAULT;                      ^^^^^^^^^^^^^^^^^^

The attached patch checks for overflow, and if it is detected, the
number of iocbs submitted is scaled down to a number that will fit in
the long.  This is an ok thing to do, as sys_io_submit is documented as
returning the number of iocbs submitted, so callers should handle a
return value of less than the 'nr' argument passed in.

Reported-by: Tavis Ormandy <taviso@cmpxchg8b.com>
Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fs/aio.c