Return-Path: linux-nfs-owner@vger.kernel.org Received: from mx1.redhat.com ([209.132.183.28]:59223 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756204AbaISOg0 (ORCPT ); Fri, 19 Sep 2014 10:36:26 -0400 Message-ID: <541C3F67.7000300@RedHat.com> Date: Fri, 19 Sep 2014 10:36:23 -0400 From: Steve Dickson MIME-Version: 1.0 To: Todd Vierling CC: linux-nfs@vger.kernel.org Subject: Re: [PATCH v2] exportfs: Properly parse IPv6 literal strings with null termination References: <1411060744-14328-1-git-send-email-todd.vierling@oracle.com> In-Reply-To: <1411060744-14328-1-git-send-email-todd.vierling@oracle.com> Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-nfs-owner@vger.kernel.org List-ID: On 09/18/2014 01:19 PM, Todd Vierling wrote: > 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 Committed... steved. > --- > 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; > } > >