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>
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 @@
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;