scsi: scsi_devinfo: cleanly zero-pad devinfo strings

BugLink: https://bugs.launchpad.net/bugs/1811077

commit 81df022b upstream.

Cleanly fill memory for "vendor" and "model" with 0-bytes for the
"compatible" case rather than adding only a single 0 byte.  This
simplifies the devinfo code a a bit, and avoids mistakes in other places
of the code (not in current upstream, but we had one such mistake in the
SUSE kernel).

[mkp: applied by hand and added braces]
Signed-off-by: Martin Wilck <mwilck@suse.com>
Reviewed-by: Bart Van Assche <bart.vanassche@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

drivers/scsi/scsi_devinfo.c

@@ -33,7 +33,6 @@ struct scsi_dev_info_list_table {
 };
 
 
-static const char spaces[] = "                "; /* 16 of them */
 static unsigned scsi_default_dev_flags;
 static LIST_HEAD(scsi_dev_info_list);
 static char scsi_dev_flags[256];
@@ -293,20 +292,13 @@ static void scsi_strcpy_devinfo(char *name, char *to, size_t to_length,
 	size_t from_length;
 
 	from_length = strlen(from);
-	strncpy(to, from, min(to_length, from_length));
-	if (from_length < to_length) {
-		if (compatible) {
-			/*
-			 * NUL terminate the string if it is short.
-			 */
-			to[from_length] = '\0';
-		} else {
-			/* 
-			 * space pad the string if it is short. 
-			 */
-			strncpy(&to[from_length], spaces,
-				to_length - from_length);
-		}
+	/* this zero-pads the destination */
+	strncpy(to, from, to_length);
+	if (from_length < to_length && !compatible) {
+		/*
+		 * space pad the string if it is short.
+		 */
+		memset(&to[from_length], ' ', to_length - from_length);
 	}
 	if (from_length > to_length)
 		 printk(KERN_WARNING "%s: %s string '%s' is too long\n",