bin/188951: Undefined behavior at line 135 in part_wizard.c (snprintf).

[Henning Petersen]

>Number:         188951
>Category:       bin
>Synopsis:       Undefined behavior at line 135 in part_wizard.c (snprintf).
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Thu Apr 24 11:40:00 UTC 2014
>Closed-Date:
>Last-Modified:
>Originator:     Henning Petersen
>Release:        FreeBSD-current
>Organization:
>Environment:
>Description:
Undefined behavior in snprintf found by cppcheck.
>How-To-Repeat:

>Fix:


Patch attached with submission follows:

--- usr.sbin/bsdinstall/partedit/part_wizard.c	(revision 264867)
+++ usr.sbin/bsdinstall/partedit/part_wizard.c	(working copy)
@@ -130,9 +130,13 @@
 				else
 					strcat(diskdesc, " Disk");
 
-				if (desc != NULL)
-					snprintf(diskdesc, sizeof(diskdesc),
-					    "%s <%s>", diskdesc, desc);
+				if (desc != NULL) {
+					size_t len;
+					len = strlen(diskdesc);
+					snprintf(diskdesc + len,
+						 sizeof(diskdesc) - len,
+					    " <%s>", desc);
+				}
 
 				disks[n-1].text = strdup(diskdesc);
 				disks[n-1].help = NULL;


>Release-Note:
>Audit-Trail:
>Unformatted: