From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from relay.sgi.com (relay1.corp.sgi.com [137.38.102.111]) by oss.sgi.com (Postfix) with ESMTP id 66B4A7F37 for ; Wed, 7 Oct 2015 11:48:56 -0500 (CDT) Received: from cuda.sgi.com (cuda1.sgi.com [192.48.157.11]) by relay1.corp.sgi.com (Postfix) with ESMTP id 482398F8066 for ; Wed, 7 Oct 2015 09:48:53 -0700 (PDT) Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) by cuda.sgi.com with ESMTP id WXpRXrmsI0QFV7x0 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO) for ; Wed, 07 Oct 2015 09:48:52 -0700 (PDT) Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) by mx1.redhat.com (Postfix) with ESMTPS id D398733E5EC for ; Wed, 7 Oct 2015 16:48:51 +0000 (UTC) Date: Wed, 7 Oct 2015 11:48:48 -0500 From: "Bill O'Donnell" Subject: Re: [PATCH] xfs: avoid null *src in memcpy call in xlog_write Message-ID: <20151007164848.GA22636@redhat.com> References: <56154967.70100@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <56154967.70100@redhat.com> List-Id: XFS Filesystem from SGI List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: xfs-bounces@oss.sgi.com Sender: xfs-bounces@oss.sgi.com To: Eric Sandeen Cc: xfs@oss.sgi.com Looks good to me. Reviewed-by: Bill O'Donnell On Wed, Oct 07, 2015 at 11:33:43AM -0500, Eric Sandeen wrote: > The gcc undefined behavior sanitizer caught this; surely > any sane memcpy implementation will no-op if size == 0, > but behavior with a *src of NULL is technically undefined > (declared nonnull), so avoid it here. > > We are actually in this situation frequently via > xlog_commit_record(), because: > > struct xfs_log_iovec reg = { > .i_addr = NULL, > .i_len = 0, > .i_type = XLOG_REG_TYPE_COMMIT, > }; > > Signed-off-by: Eric Sandeen > --- > > diff --git a/fs/xfs/xfs_log.c b/fs/xfs/xfs_log.c > index 4012523..8897fd1 100644 > --- a/fs/xfs/xfs_log.c > +++ b/fs/xfs/xfs_log.c > @@ -2424,7 +2424,10 @@ xlog_write( > > /* copy region */ > ASSERT(copy_len >= 0); > - memcpy(ptr, reg->i_addr + copy_off, copy_len); > + ASSERT(reg->i_addr + copy_off > 0 || copy_len == 0); > + /* size == 0 is ok, but *src == NULL is undefined */ > + if (reg->i_addr + copy_off) > + memcpy(ptr, reg->i_addr + copy_off, copy_len); > xlog_write_adv_cnt(&ptr, &len, &log_offset, copy_len); > > copy_len += start_rec_copy + sizeof(xlog_op_header_t); > > _______________________________________________ > xfs mailing list > xfs@oss.sgi.com > http://oss.sgi.com/mailman/listinfo/xfs _______________________________________________ xfs mailing list xfs@oss.sgi.com http://oss.sgi.com/mailman/listinfo/xfs