abb85a9b51
When iscsi WRITE underflow occurs there are two different scenarios
that can happen.
Normally in practice, when an EDTL vs. SCSI CDB TRANSFER LENGTH
underflow is detected, the iscsi immediate data payload is the
smaller SCSI CDB TRANSFER LENGTH.
That is, when a host fabric LLD is using a fixed size EDTL for
a specific control CDB, the SCSI CDB TRANSFER LENGTH and actual
SCSI payload ends up being smaller than EDTL. In iscsi, this
means the received iscsi immediate data payload matches the
smaller SCSI CDB TRANSFER LENGTH, because there is no more
SCSI payload to accept beyond SCSI CDB TRANSFER LENGTH.
However, it's possible for a malicous host to send a WRITE
underflow where EDTL is larger than SCSI CDB TRANSFER LENGTH,
but incoming iscsi immediate data actually matches EDTL.
In the wild, we've never had a iscsi host environment actually
try to do this.
For this special case, it's wrong to truncate part of the
control CDB payload and continue to process the command during
underflow when immediate data payload received was larger than
SCSI CDB TRANSFER LENGTH, so go ahead and reject and drop the
bogus payload as a defensive action.
Note this potential bug was originally relaxed by the following
for allowing WRITE underflow in MSFT FCP host environments:
commit c72c5250224d475614a00c1d7e54a67f77cd3410
Author: Roland Dreier <roland@purestorage.com>
Date: Wed Jul 22 15:08:18 2015 -0700
target: allow underflow/overflow for PR OUT etc. commands
Cc: Roland Dreier <roland@purestorage.com>
Cc: Mike Christie <mchristi@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Cc: Martin K. Petersen <martin.petersen@oracle.com>
Cc: <stable@vger.kernel.org> # v4.3+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.