PERFORCE change 32072 for review

[Robert Watson]

http://perforce.freebsd.org/chv.cgi?CH=32072

Change 32072 by rwatson at rwatson_tislabs on 2003/05/29 16:14:02

	Temporary work-around for overflows in externalization of
	compartment strings in the Biba and MLS policies.  Validate
	that the nul we slap down in fact lands inside the string.
	This code generally needs cleaning up, since it fails to
	handle failures by snprintf().  If the provided string is
	too short, this result is preferable to kernel panics, etc.

Affected files ...

.. //depot/projects/trustedbsd/mac/sys/security/mac_biba/mac_biba.c#209 edit
.. //depot/projects/trustedbsd/mac/sys/security/mac_mls/mac_mls.c#167 edit

Differences ...

==== //depot/projects/trustedbsd/mac/sys/security/mac_biba/mac_biba.c#209 (text+ko) ====

@@ -583,7 +583,11 @@
 		} while(bit <= MAC_BIBA_MAX_COMPARTMENTS);
 
 		len = size - left - 1;
-		string[len] = '\0';
+		if (len > 0 && len < size)
+			string[len] = '\0';
+		else
+			string[0] = '\0';
+			
 		return (len);
 
 	default:

==== //depot/projects/trustedbsd/mac/sys/security/mac_mls/mac_mls.c#167 (text+ko) ====

@@ -547,7 +547,10 @@
 		} while(bit <= MAC_MLS_MAX_COMPARTMENTS);
 
 		len = size - left - 1;
-		string[len] = '\0';
+		if (len > 0 && len < size)
+			string[len] = '\0';
+		else
+			string[0] = '\0';
 		return (len);
 
 	default: