Date: Sat, 23 Feb 2008 14:57:17 GMT From: Joerg Wallerich <joerg@net.t-labs.tu-berlin.de> To: freebsd-gnats-submit@FreeBSD.org Subject: bin/120994: alignment violation in chap module of ppp(8) causes bus error on ARM Message-ID: <200802231457.m1NEvHxh040535@www.freebsd.org> Resent-Message-ID: <200802231500.m1NF084o005857@freefall.freebsd.org>
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>Number: 120994 >Category: bin >Synopsis: alignment violation in chap module of ppp(8) causes bus error on ARM >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: Sat Feb 23 15:00:07 UTC 2008 >Closed-Date: >Last-Modified: >Originator: Joerg Wallerich >Release: RELENG_7 >Organization: >Environment: FreeBSD avila 7.0-PRERELEASE FreeBSD 7.0-PRERELEASE #12: Sat Feb 23 05:03:12 CET 2008 root@sulaco:/usr/obj/arm/usr/src/sys/AVILA.router arm >Description: The chap code in ppp(8) provides a target buffer to MD5Final() that is not word aligned. This leads to a bus error in libmd while computing a response to the CHAP challenge string. >How-To-Repeat: Authenticate a ppp/pppoe session unsing CHAP >Fix: Provide a temporary word aligned buffer to store the MD5 hash and copy the hash into the CHAP response string using memcpy(). Patch attached with submission follows: Index: chap.c =================================================================== RCS file: /home/ncvs/src/usr.sbin/ppp/chap.c,v retrieving revision 1.86 diff -c -r1.86 chap.c *** chap.c 5 Sep 2004 01:46:51 -0000 1.86 --- chap.c 23 Feb 2008 14:51:45 -0000 *************** *** 130,135 **** --- 130,136 ---- ) { char *result, *digest; + char *tmpbuf; size_t nlen, klen; nlen = strlen(name); *************** *** 232,237 **** --- 233,239 ---- /* Normal MD5 stuff */ MD5_CTX MD5context; + tmpbuf = malloc(nlen + 17); digest = result; *digest++ = 16; /* value size */ *************** *** 239,247 **** MD5Update(&MD5context, &id, 1); MD5Update(&MD5context, key, klen); MD5Update(&MD5context, challenge + 1, *challenge); ! MD5Final(digest, &MD5context); memcpy(digest + 16, name, nlen); /* * ---- -------- ------ * result = | 16 | digest | name | --- 241,251 ---- MD5Update(&MD5context, &id, 1); MD5Update(&MD5context, key, klen); MD5Update(&MD5context, challenge + 1, *challenge); ! MD5Final(tmpbuf, &MD5context); + memcpy(digest, tmpbuf, 16); memcpy(digest + 16, name, nlen); + free(tmpbuf); /* * ---- -------- ------ * result = | 16 | digest | name | >Release-Note: >Audit-Trail: >Unformatted:
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