Return-Path: linux-nfs-owner@vger.kernel.org Received: from userp1040.oracle.com ([156.151.31.81]:47616 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932081AbaIRRTP (ORCPT ); Thu, 18 Sep 2014 13:19:15 -0400 From: Todd Vierling To: steved@redhat.com Cc: linux-nfs@vger.kernel.org Subject: [PATCH v2] exportfs: Properly parse IPv6 literal strings with null termination Date: Thu, 18 Sep 2014 13:19:04 -0400 Message-Id: <1411060744-14328-1-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. exportfs already modifies argv contents elsewhere, so this doesn't break anything anew. Fixes: 4663c648 (exportfs: Support raw IPv6 addresses with "client:/path") Signed-off-by: Todd Vierling Reviewed-by: Chuck Lever --- 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