From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=52365 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1P7abU-0007hH-3z for qemu-devel@nongnu.org; Sun, 17 Oct 2010 17:17:17 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1P7abT-0004pl-4G for qemu-devel@nongnu.org; Sun, 17 Oct 2010 17:17:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:9366) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1P7abS-0004pg-Tf for qemu-devel@nongnu.org; Sun, 17 Oct 2010 17:17:15 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id o9HLHC4i007638 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Sun, 17 Oct 2010 17:17:13 -0400 Date: Sun, 17 Oct 2010 23:10:55 +0200 From: "Michael S. Tsirkin" Message-ID: <20101017211055.GA13854@redhat.com> References: <20101017184340.GA12524@redhat.com> <1287349305.21691.17.camel@x201> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1287349305.21691.17.camel@x201> Subject: [Qemu-devel] Re: [PATCH] migration: don't segfault on invalid input List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex Williamson Cc: qemu-devel@nongnu.org On Sun, Oct 17, 2010 at 03:01:45PM -0600, Alex Williamson wrote: > On Sun, 2010-10-17 at 20:43 +0200, Michael S. Tsirkin wrote: > > host_from_stream_offset returns NULL on error, > > return error instead of trying to use that address, > > to avoid segfault on invalid stream. > > > > Signed-off-by: Michael S. Tsirkin > > --- > > arch_init.c | 5 +++++ > > 1 files changed, 5 insertions(+), 0 deletions(-) > > > > diff --git a/arch_init.c b/arch_init.c > > index e468c0c..bc7528d 100644 > > --- a/arch_init.c > > +++ b/arch_init.c > > @@ -116,6 +116,8 @@ static int ram_save_block(QEMUFile *f) > > > > if (!block) > > block = QLIST_FIRST(&ram_list.blocks); > > + if (!last_block) > > + last_block = block; > > > > current_addr = block->offset + offset; > > NAK, last_block == block will cause us to set the continue flag on the > first block. I assume you're trying to prevent the last_block->offset > segv in the while test, but that should never happen. The only time > last_block is NULL is at the beginning of stage 1, where all pages are > dirty. At that point we should always enter the if {} block at the > beginning of the do {} while, which breaks out rather than hitting the > segv. We'll then set last_block for the next pass. Sorry, sent this chunk in error. > > @@ -390,6 +392,9 @@ int ram_load(QEMUFile *f, void *opaque, int version_id) > > host = qemu_get_ram_ptr(addr); > > else > > host = host_from_stream_offset(f, addr, flags); > > + if (!host) { > > + return -EINVAL; > > + } > > > > This should also never happen since we've synchronized ramblocks at the > beginning of migration, but probably a good idea to return an error. > Thanks, > > Alex