From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:41719) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1WUd0x-0000N5-59 for qemu-devel@nongnu.org; Mon, 31 Mar 2014 10:16:43 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1WUd0r-0000du-V0 for qemu-devel@nongnu.org; Mon, 31 Mar 2014 10:16:39 -0400 Date: Mon, 31 Mar 2014 17:16:55 +0300 From: "Michael S. Tsirkin" Message-ID: <1396275242-10810-16-git-send-email-mst@redhat.com> References: <1396275242-10810-1-git-send-email-mst@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1396275242-10810-1-git-send-email-mst@redhat.com> Subject: [Qemu-devel] [PATCH v4 15/30] stellaris_enet: avoid buffer orerrun on incoming migration (part 3) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , qemu-stable@nongnu.org, dgilbert@redhat.com, mdroth@linux.vnet.ibm.com CVE-2013-4532 s->tx_frame_len is read from the wire and can later used as an index into s->tx_fifo[] for memset() when a DATA command is issued by the guest. In this case s->tx_frame_len is checked to avoid an overrun, but if the value is negative a subsequently executed guest can underrun the buffer with zeros via the memset() call. Additionally, tx_frame_len is used to validate that tx_fifo_len doesn't exceed the fifo bounds - the assumption being that data model never makes it exceed 2032. Fix this by failing migration if the incoming value of s->tx_frame_len is less than -1 (the emulation code allows from -1 as a special case) or if it exceeds 2032. Reported-by: Michael Roth Reported-by: Peter Maydell Signed-off-by: Michael S. Tsirkin --- hw/net/stellaris_enet.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/hw/net/stellaris_enet.c b/hw/net/stellaris_enet.c index aed00fd..90ff950 100644 --- a/hw/net/stellaris_enet.c +++ b/hw/net/stellaris_enet.c @@ -373,7 +373,11 @@ static int stellaris_enet_load(QEMUFile *f, void *opaque, int version_id) s->mtxd = qemu_get_be32(f); s->mrxd = qemu_get_be32(f); s->np = qemu_get_be32(f); - s->tx_frame_len = qemu_get_be32(f); + v = qemu_get_be32(f); + if (v < -1 || s->tx_frame_len > 2032) { + return -EINVAL; + } + s->tx_frame_len = v; v = qemu_get_be32(f); /* How many bytes does data use in tx fifo. */ sz = s->tx_frame_len == -1 ? 2 : 4; -- MST