From be18992d0630149403bfae5882601cf01a7d4eea Mon Sep 17 00:00:00 2001 From: Jeff Moyer Date: Fri, 10 Sep 2010 14:16:00 -0700 Subject: [PATCH 4/4] 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:        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 --- fs/aio.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/fs/aio.c b/fs/aio.c index 02a2c93..b84a769 100644 --- a/fs/aio.c +++ b/fs/aio.c @@ -1639,6 +1639,9 @@ SYSCALL_DEFINE3(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; -- 1.7.2.3