From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35028) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Zbowi-0007x5-Q6 for qemu-devel@nongnu.org; Tue, 15 Sep 2015 08:02:55 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Zbowe-0002oV-6s for qemu-devel@nongnu.org; Tue, 15 Sep 2015 08:02:48 -0400 From: Stefan Hajnoczi Date: Tue, 15 Sep 2015 13:02:29 +0100 Message-Id: <1442318551-27609-2-git-send-email-stefanha@redhat.com> In-Reply-To: <1442318551-27609-1-git-send-email-stefanha@redhat.com> References: <1442318551-27609-1-git-send-email-stefanha@redhat.com> Subject: [Qemu-devel] [PULL 1/3] e1000: Avoid infinite loop in processing transmit descriptor (CVE-2015-6815) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: Peter Maydell , qemu-stable@nongnu.org, Stefan Hajnoczi , P J P From: P J P While processing transmit descriptors, it could lead to an infinite loop if 'bytes' was to become zero; Add a check to avoid it. [The guest can force 'bytes' to 0 by setting the hdr_len and mss descriptor fields to 0. --Stefan] Signed-off-by: P J P Signed-off-by: Stefan Hajnoczi Reviewed-by: Thomas Huth Message-id: 1441383666-6590-1-git-send-email-stefanha@redhat.com --- hw/net/e1000.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/hw/net/e1000.c b/hw/net/e1000.c index 5c6bcd0..09c9e9d 100644 --- a/hw/net/e1000.c +++ b/hw/net/e1000.c @@ -740,7 +740,8 @@ process_tx_desc(E1000State *s, struct e1000_tx_desc *dp) memmove(tp->data, tp->header, tp->hdr_len); tp->size = tp->hdr_len; } - } while (split_size -= bytes); + split_size -= bytes; + } while (bytes && split_size); } else if (!tp->tse && tp->cptse) { // context descriptor TSE is not set, while data descriptor TSE is set DBGOUT(TXERR, "TCP segmentation error\n"); -- 2.4.3