Return-Path: linux-nfs-owner@vger.kernel.org Received: from userp1040.oracle.com ([156.151.31.81]:37541 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751750AbaIQXso (ORCPT ); Wed, 17 Sep 2014 19:48:44 -0400 Received: from ucsinet22.oracle.com (ucsinet22.oracle.com [156.151.31.94]) by userp1040.oracle.com (Sentrion-MTA-4.3.2/Sentrion-MTA-4.3.2) with ESMTP id s8HNmfTb010756 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Wed, 17 Sep 2014 23:48:42 GMT From: Todd Vierling To: linux-nfs@vger.kernel.org Subject: [PATCH] exportfs: Properly parse IPv6 literal strings with null termination Date: Wed, 17 Sep 2014 19:48:39 -0400 Message-Id: <1410997719-17913-1-git-send-email-todd.vierling@oracle.com> Sender: linux-nfs-owner@vger.kernel.org List-ID: The original implementation was using strncpy() with a truncation length to an uninitialized stack buffer, leaving a string that was only null terminated by luck. While here, change to use no-copy semantics (no extra buffer) to avoid buffer overflows altogether. --- utils/exportfs/exportfs.c | 18 ++++++++---------- 1 file changed, 8 insertions(+), 10 deletions(-) diff --git a/utils/exportfs/exportfs.c b/utils/exportfs/exportfs.c index e7d1ac8..bdea12b 100644 --- a/utils/exportfs/exportfs.c +++ b/utils/exportfs/exportfs.c @@ -351,16 +351,15 @@ static int exportfs_generic(char *arg, char *options, int verbose) static int exportfs_ipv6(char *arg, char *options, int verbose) { - char *path, *c, hname[NI_MAXHOST + strlen("/128")]; + char *path, *c; arg++; c = strchr(arg, ']'); if (c == NULL) return 1; - strncpy(hname, arg, c - arg); /* no colon means this is a wildcarded DNS hostname */ - if (strchr(hname, ':') == NULL) + if (memchr(arg, ':', c - arg) == NULL) return exportfs_generic(--arg, options, verbose); path = strstr(c, ":/"); @@ -370,9 +369,9 @@ static int exportfs_ipv6(char *arg, char *options, int verbose) /* if there's anything between the closing brace and the * path separator, it's probably a prefix length */ - strcat(hname, ++c); + memmove(c, c + 1, path - c); - exportfs_parsed(hname, path, options, verbose); + exportfs_parsed(arg, path, options, verbose); return 0; } @@ -458,16 +457,15 @@ static int unexportfs_generic(char *arg, int verbose) static int unexportfs_ipv6(char *arg, int verbose) { - char *path, *c, hname[NI_MAXHOST + strlen("/128")]; + char *path, *c; arg++; c = strchr(arg, ']'); if (c == NULL) return 1; - strncpy(hname, arg, c - arg); /* no colon means this is a wildcarded DNS hostname */ - if (strchr(hname, ':') == NULL) + if (memchr(arg, ':', c - arg) == NULL) return unexportfs_generic(--arg, verbose); path = strstr(c, ":/"); @@ -477,9 +475,9 @@ static int unexportfs_ipv6(char *arg, int verbose) /* if there's anything between the closing brace and the * path separator, it's probably a prefix length */ - strcat(hname, ++c); + memmove(c, c + 1, path - c); - unexportfs_parsed(hname, path, verbose); + unexportfs_parsed(arg, path, verbose); return 0; } -- 1.8.3.1