From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com ([209.132.183.28]:56220 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727673AbfDWPHV (ORCPT ); Tue, 23 Apr 2019 11:07:21 -0400 Date: Tue, 23 Apr 2019 10:07:14 -0500 From: Bill O'Donnell Subject: Re: [PATCH 06/10] misc: fix strncpy length complaints Message-ID: <20190423150714.GA4998@redhat.com> References: <155594788997.115924.16224143537288136652.stgit@magnolia> <155594792809.115924.2016290538799986694.stgit@magnolia> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <155594792809.115924.2016290538799986694.stgit@magnolia> Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: "Darrick J. Wong" Cc: sandeen@sandeen.net, linux-xfs@vger.kernel.org On Mon, Apr 22, 2019 at 08:45:28AM -0700, Darrick J. Wong wrote: > From: Darrick J. Wong > > Fix a number of complaints about feeding sizeof(dest) directly to > strncpy. We do this by declaring the char arrays to be one larger > than necessary and subtracting one, to ensure that we never overfill > the buffer. > > Signed-off-by: Darrick J. Wong > --- Reviewed-by: Bill O'Donnell > mkfs/xfs_mkfs.c | 13 +++++++++++-- > quota/edit.c | 9 ++++++--- > 2 files changed, 17 insertions(+), 5 deletions(-) > > > diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c > index 3e2ef92d..db3ad38e 100644 > --- a/mkfs/xfs_mkfs.c > +++ b/mkfs/xfs_mkfs.c > @@ -3270,8 +3270,17 @@ finish_superblock_setup( > struct xfs_mount *mp, > struct xfs_sb *sbp) > { > - if (cfg->label) > - strncpy(sbp->sb_fname, cfg->label, sizeof(sbp->sb_fname)); > + if (cfg->label) { > + size_t label_len; > + > + /* > + * Labels are null terminated unless the string fits exactly > + * in the label field, so assume sb_fname is zeroed and then > + * do a memcpy because the destination isn't a normal C string. > + */ > + label_len = min(sizeof(sbp->sb_fname), strlen(cfg->label)); > + memcpy(sbp->sb_fname, cfg->label, label_len); > + } > > sbp->sb_dblocks = cfg->dblocks; > sbp->sb_rblocks = cfg->rtblocks; > diff --git a/quota/edit.c b/quota/edit.c > index b10a5b34..f9938b8a 100644 > --- a/quota/edit.c > +++ b/quota/edit.c > @@ -368,8 +368,7 @@ restore_file( > uint type) > { > char buffer[512]; > - char devbuffer[512]; > - char *dev = NULL; > + char dev[512]; > uint mask; > int cnt; > uint32_t id; > @@ -377,7 +376,11 @@ restore_file( > > while (fgets(buffer, sizeof(buffer), fp) != NULL) { > if (strncmp("fs = ", buffer, 5) == 0) { > - dev = strncpy(devbuffer, buffer+5, sizeof(devbuffer)); > + /* > + * Copy the device name to dev, strip off the trailing > + * newline, and move on to the next line. > + */ > + strncpy(dev, buffer + 5, sizeof(dev) - 1); > dev[strlen(dev) - 1] = '\0'; > continue; > } >