tree f3056dc8de11ab4431cb227f4417af810c7f31e9
parent a72d9002f80bffd7e4c7d60e5a9caa0cddffe894
author David Vrabel <david.vrabel@citrix.com> 1362677521 +0000
committer Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> 1363024468 -0400

xen/blkback: correctly respond to unknown, non-native requests

If the frontend is using a non-native protocol (e.g., a 64-bit
frontend with a 32-bit backend) and it sent an unrecognized request,
the request was not translated and the response would have the
incorrect ID.  This may cause the frontend driver to behave
incorrectly or crash.

Since the ID field in the request is always in the same place,
regardless of the request type we can get the correct ID and make a
valid response (which will report BLKIF_RSP_EOPNOTSUPP).

This bug affected 64-bit SLES 11 guests when using a 32-bit backend.
This guest does a BLKIF_OP_RESERVED_1 (BLKIF_OP_PACKET in the SLES
source) and would crash in blkif_int() as the ID in the response would
be invalid.

Signed-off-by: David Vrabel <david.vrabel@citrix.com>
Cc: stable@vger.kernel.org
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>