This bug has been copied from bug #664592 and has been proposed
to be backported to 5.6 z-stream (EUS).
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.
Technical note added. If any revisions are required, please edit the "Technical Notes" field
accordingly. All revisions will be proofread by the Engineering Content Services team.
Using the cciss driver, when a TUR (Test Unit Ready) was executed, the rq->bio pointer in the blk_rq_bytes function was of value null, which resulted in a null pointer dereference, and, consequently, kernel panic occurred. With this update, the rq->bio pointer is used only when the blk_fs_request(rq) condition is true, thus, kernel panic no longer occurs.