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authorNicholas Bellinger <nab@linux-iscsi.org>2017-06-07 20:29:50 -0700
committerNicholas Bellinger <nab@linux-iscsi.org>2017-06-08 22:25:29 -0700
commitabb85a9b512e8ca7ad04a5a8a6db9664fe644974 (patch)
treea245ad14275d493f72afb3a55a2f067fc97e34de /drivers/target/iscsi
parent105fa2f44e504c830697b0c794822112d79808dc (diff)
downloadlinux-stericsson-abb85a9b512e8ca7ad04a5a8a6db9664fe644974.tar.gz
iscsi-target: Reject immediate data underflow larger than SCSI transfer length
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>
Diffstat (limited to 'drivers/target/iscsi')
-rw-r--r--drivers/target/iscsi/iscsi_target.c12
1 files changed, 12 insertions, 0 deletions
diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index c0254516b380..3fdca2cdd8da 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -1279,6 +1279,18 @@ iscsit_get_immediate_data(struct iscsi_cmd *cmd, struct iscsi_scsi_req *hdr,
*/
if (dump_payload)
goto after_immediate_data;
+ /*
+ * Check for underflow case where both EDTL and immediate data payload
+ * exceeds what is presented by CDB's TRANSFER LENGTH, and what has
+ * already been set in target_cmd_size_check() as se_cmd->data_length.
+ *
+ * For this special case, fail the command and dump the immediate data
+ * payload.
+ */
+ if (cmd->first_burst_len > cmd->se_cmd.data_length) {
+ cmd->sense_reason = TCM_INVALID_CDB_FIELD;
+ goto after_immediate_data;
+ }
immed_ret = iscsit_handle_immediate_data(cmd, hdr,
cmd->first_burst_len);