block: Limit request size (CVE-2014-0143)

block: Limit request size (CVE-2014-0143)

Limiting the size of a single request to INT_MAX not only fixes a
direct integer overflow in bdrv_check_request() (which would only
trigger bad behaviour with ridiculously huge images, as in close to
2^64 bytes), but can also prevent overflows in all block drivers.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 8f4754ede56e3f9ea3fd7207f4a7c4453e59285b)
Signed-off-by: Michael Roth <mdroth@linux.vnet.ibm.com>