s390/dasd: fix string length handling

Building dasd_eckd.o with latest clang reveals this bug:

    CC      drivers/s390/block/dasd_eckd.o
      drivers/s390/block/dasd_eckd.c:1082:3: warning: 'snprintf' will always be truncated;
      specified size is 1, but format string expands to at least 11 [-Wfortify-source]
       1082 |                 snprintf(print_uid, sizeof(*print_uid),
            |                 ^
      drivers/s390/block/dasd_eckd.c:1087:3: warning: 'snprintf' will always be truncated;
      specified size is 1, but format string expands to at least 10 [-Wfortify-source]
       1087 |                 snprintf(print_uid, sizeof(*print_uid),
            |                 ^

Fix this by moving and using the existing UID_STRLEN for the arrays
that are being written to. Also rename UID_STRLEN to DASD_UID_STRLEN
to clarify its scope.

Fixes: 2359696 ("s390/dasd: split up dasd_eckd_read_conf")
Reviewed-by: Peter Oberparleiter <oberpar@linux.ibm.com>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com> # build
Reported-by: Nathan Chancellor <nathan@kernel.org>
Closes: ClangBuiltLinux#1923
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Link: https://lore.kernel.org/r/20230828153142.2843753-2-hca@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: hcahca

drivers/s390/block/dasd_devmap.c

@@ -1378,16 +1378,12 @@ static ssize_t dasd_vendor_show(struct device *dev,
 
 static DEVICE_ATTR(vendor, 0444, dasd_vendor_show, NULL);
 
-#define UID_STRLEN ( /* vendor */ 3 + 1 + /* serial    */ 14 + 1 +\
-		     /* SSID   */ 4 + 1 + /* unit addr */ 2 + 1 +\
-		     /* vduit */ 32 + 1)
-
 static ssize_t
 dasd_uid_show(struct device *dev, struct device_attribute *attr, char *buf)
 {
+	char uid_string[DASD_UID_STRLEN];
 	struct dasd_device *device;
 	struct dasd_uid uid;
-	char uid_string[UID_STRLEN];
 	char ua_string[3];
 
 	device = dasd_device_from_cdev(to_ccwdev(dev));

drivers/s390/block/dasd_eckd.c

@@ -1079,12 +1079,12 @@ static void dasd_eckd_get_uid_string(struct dasd_conf *conf,
 
 	create_uid(conf, &uid);
 	if (strlen(uid.vduit) > 0)
-		snprintf(print_uid, sizeof(*print_uid),
+		snprintf(print_uid, DASD_UID_STRLEN,
 			 "%s.%s.%04x.%02x.%s",
 			 uid.vendor, uid.serial, uid.ssid,
 			 uid.real_unit_addr, uid.vduit);
 	else
-		snprintf(print_uid, sizeof(*print_uid),
+		snprintf(print_uid, DASD_UID_STRLEN,
 			 "%s.%s.%04x.%02x",
 			 uid.vendor, uid.serial, uid.ssid,
 			 uid.real_unit_addr);
@@ -1093,8 +1093,8 @@ static void dasd_eckd_get_uid_string(struct dasd_conf *conf,
 static int dasd_eckd_check_cabling(struct dasd_device *device,
 				   void *conf_data, __u8 lpm)
 {
+	char print_path_uid[DASD_UID_STRLEN], print_device_uid[DASD_UID_STRLEN];
 	struct dasd_eckd_private *private = device->private;
-	char print_path_uid[60], print_device_uid[60];
 	struct dasd_conf path_conf;
 
 	path_conf.data = conf_data;
@@ -1293,9 +1293,9 @@ static void dasd_eckd_path_available_action(struct dasd_device *device,
 	__u8 path_rcd_buf[DASD_ECKD_RCD_DATA_SIZE];
 	__u8 lpm, opm, npm, ppm, epm, hpfpm, cablepm;
 	struct dasd_conf_data *conf_data;
+	char print_uid[DASD_UID_STRLEN];
 	struct dasd_conf path_conf;
 	unsigned long flags;
-	char print_uid[60];
 	int rc, pos;
 
 	opm = 0;
@@ -5855,8 +5855,8 @@ static void dasd_eckd_dump_sense(struct dasd_device *device,
 static int dasd_eckd_reload_device(struct dasd_device *device)
 {
 	struct dasd_eckd_private *private = device->private;
+	char print_uid[DASD_UID_STRLEN];
 	int rc, old_base;
-	char print_uid[60];
 	struct dasd_uid uid;
 	unsigned long flags;
 

drivers/s390/block/dasd_int.h

@@ -259,6 +259,10 @@ struct dasd_uid {
 	char vduit[33];
 };
 
+#define DASD_UID_STRLEN ( /* vendor */ 3 + 1 + /* serial    */ 14 + 1 +	\
+			  /* SSID   */ 4 + 1 + /* unit addr */ 2 + 1 +	\
+			  /* vduit */ 32 + 1)
+
 /*
  * PPRC Status data
  */