From: Jeff Moyer Date: Fri, 10 Sep 2010 21:16:00 +0000 (-0700) Subject: aio: check for multiplication overflow in do_io_submit X-Git-Tag: v2.6.36-rc5~37 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=75e1c70fc31490ef8a373ea2a4bea2524099b478;p=platform%2Fkernel%2Flinux-exynos.git 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 Signed-off-by: Jeff Moyer Signed-off-by: Linus Torvalds --- diff --git a/fs/aio.c b/fs/aio.c index 3006b5b..1320b2a 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -1659,6 +1659,9 @@ long do_io_submit(aio_context_t ctx_id, long nr, if (unlikely(nr < 0)) return -EINVAL; + if (unlikely(nr > LONG_MAX/sizeof(*iocbpp))) + nr = LONG_MAX/sizeof(*iocbpp); + if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(*iocbpp))))) return -EFAULT;