scsi: target: fix PR IN / READ FULL STATUS for FC

BugLink: https://bugs.launchpad.net/bugs/1878098

[ Upstream commit 8fed04eb ]

Creation of the response to READ FULL STATUS fails for FC based
reservations. Reason is the too high loop limit (< 24) in
fc_get_pr_transport_id(). The string representation of FC WWPN is 23 chars
long only ("11:22:33:44:55:66:77:88"). So when i is 23, the loop body is
executed a last time for the ending '\0' of the string and thus hex2bin()
reports an error.

Link: https://lore.kernel.org/r/20200408132610.14623-3-bstroesser@ts.fujitsu.comSigned-off-by: Bodo Stroesser <bstroesser@ts.fujitsu.com>
Reviewed-by: Mike Christie <mchristi@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Ian May <ian.may@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/target/target_core_fabric_lib.c

@@ -75,7 +75,7 @@ static int fc_get_pr_transport_id(
 	 * encoded TransportID.
 	 */
 	ptr = &se_nacl->initiatorname[0];
-	for (i = 0; i < 24; ) {
+	for (i = 0; i < 23; ) {
 		if (!strncmp(&ptr[i], ":", 1)) {
 			i++;
 			continue;