From 75e1c70fc31490ef8a373ea2a4bea2524099b478 Mon Sep 17 00:00:00 2001 From: Jeff Moyer <jmoyer@redhat.com> Date: Fri, 10 Sep 2010 14:16:00 -0700 Subject: [PATCH] aio: check for multiplication overflow in do_io_submit MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Tavis Ormandy pointed out that do_io_submit does not do proper bounds checking on the passed-in iocb array: Â Â Â Â if (unlikely(nr < 0)) Â Â Â Â Â Â Â Â return -EINVAL; Â Â Â Â if (unlikely(!access_ok(VERIFY_READ, iocbpp, (nr*sizeof(iocbpp))))) Â Â Â Â Â Â Â Â return -EFAULT; Â Â Â Â Â Â Â Â Â Â Â ^^^^^^^^^^^^^^^^^^ 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. Â 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 | 3 +++ 1 file changed, 3 insertions(+) diff --git a/fs/aio.c b/fs/aio.c index 3006b5bc33d69..1320b2a05fb2a 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; -- GitLab