linux-kernel - [PATCH 1/1] s390/dasd: fix string length handling

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Message-Id: <20230828153142.2843753-2-hca@linux.ibm.com>
Date:   Mon, 28 Aug 2023 17:31:42 +0200
From:   Heiko Carstens <hca@...ux.ibm.com>
To:     Jens Axboe <axboe@...nel.dk>
Cc:     Stefan Haberland <sth@...ux.ibm.com>,
        Jan Höppner <hoeppner@...ux.ibm.com>,
        Peter Oberparleiter <oberpar@...ux.ibm.com>,
        linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-block@...r.kernel.org
Subject: [PATCH 1/1] 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: 23596961b437 ("s390/dasd: split up dasd_eckd_read_conf")
Reviewed-by: Peter Oberparleiter <oberpar@...ux.ibm.com>
Signed-off-by: Heiko Carstens <hca@...ux.ibm.com>
---
 drivers/s390/block/dasd_devmap.c |  6 +-----
 drivers/s390/block/dasd_eckd.c   | 10 +++++-----
 drivers/s390/block/dasd_int.h    |  4 ++++
 3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/drivers/s390/block/dasd_devmap.c b/drivers/s390/block/dasd_devmap.c
index 620fab01b710..c4e36650c426 100644
--- a/drivers/s390/block/dasd_devmap.c
+++ b/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));
diff --git a/drivers/s390/block/dasd_eckd.c b/drivers/s390/block/dasd_eckd.c
index 8587e423169e..bd89b032968a 100644
--- a/drivers/s390/block/dasd_eckd.c
+++ b/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;
 
diff --git a/drivers/s390/block/dasd_int.h b/drivers/s390/block/dasd_int.h
index 0aa56351da72..8a4dbe9d7741 100644
--- a/drivers/s390/block/dasd_int.h
+++ b/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
  */
-- 
2.39.2