Module Name:    src
Committed By:   kamil
Date:           Mon Jun 11 17:45:51 UTC 2018

Modified Files:
        src/sbin/ifconfig: af_inet.c

Log Message:
Correct Undefined Behavior in ifconfig(8)

Unportable left shift reported with MKSANITIZER=yes USE_SANITIZER=undefined:

# ifconfig
alc0: flags=0x8843<UP,BROADCAST,RUNNING,SIMPLEX,MULTICAST> mtu 1500
        ec_capabilities=3<VLAN_MTU,VLAN_HWTAGGING>
        ec_enabled=0
        address: xx:xx:xx:xx:xx:xx
/public/src.git/sbin/ifconfig/af_inet.c:102:34: runtime error: left shift of 
16777215 by 8 places cannot be represented in type 'int'
        inet 192.168.0.38/24 broadcast 192.168.0.255 flags 0x0
        inet6 xxxx::xxxx:xxxx:xxxx:xxx%alc0/64 flags 0x0 scopeid 0x1
lo0: flags=0x8049<UP,LOOPBACK,RUNNING,MULTICAST> mtu 33624
        inet 127.0.0.1/8 flags 0x0
        inet6 ::1/128 flags 0x20<NODAD>
        inet6 fe80::1%lo0/64 flags 0x0 scopeid 0x2

Change shifting left 1 to shifting 1U. This corrects the issue.

        if (cidr < 32) {                /* more than 1 bit in mask */
                /* check for non-contig netmask */
                if ((mask ^ (((1 << cidr) - 1) << (32 - cidr))) != 0) // <- here
                        return -1;      /* noncontig, no pfxlen */
        }

Solution suggested by <uwe>

Sponsored by <The NetBSD Foundation>


To generate a diff of this commit:
cvs rdiff -u -r1.24 -r1.25 src/sbin/ifconfig/af_inet.c

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.

Modified files:

Index: src/sbin/ifconfig/af_inet.c
diff -u src/sbin/ifconfig/af_inet.c:1.24 src/sbin/ifconfig/af_inet.c:1.25
--- src/sbin/ifconfig/af_inet.c:1.24	Sat Oct  1 20:59:49 2016
+++ src/sbin/ifconfig/af_inet.c	Mon Jun 11 17:45:50 2018
@@ -1,4 +1,4 @@
-/*	$NetBSD: af_inet.c,v 1.24 2016/10/01 20:59:49 kre Exp $	*/
+/*	$NetBSD: af_inet.c,v 1.25 2018/06/11 17:45:50 kamil Exp $	*/
 
 /*
  * Copyright (c) 1983, 1993
@@ -31,7 +31,7 @@
 
 #include <sys/cdefs.h>
 #ifndef lint
-__RCSID("$NetBSD: af_inet.c,v 1.24 2016/10/01 20:59:49 kre Exp $");
+__RCSID("$NetBSD: af_inet.c,v 1.25 2018/06/11 17:45:50 kamil Exp $");
 #endif /* not lint */
 
 #include <sys/param.h> 
@@ -99,7 +99,7 @@ in_prefixlen(struct sockaddr *sa)
 
 	if (cidr < 32) {		/* more than 1 bit in mask */
 		/* check for non-contig netmask */
-		if ((mask ^ (((1 << cidr) - 1) << (32 - cidr))) != 0)
+		if ((mask ^ (((1U << cidr) - 1) << (32 - cidr))) != 0)
 			return -1;	/* noncontig, no pfxlen */
 	}
 

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