e1000: Avoid infinite loop in processing transmit descriptor (CVE-2015-6815)

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 <pjp@fedoraproject.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-id: 1441383666-6590-1-git-send-email-stefanha@redhat.com
This commit is contained in:
P J P 2015-09-04 17:21:06 +01:00 committed by Stefan Hajnoczi
parent 2752e5bedb
commit b947ac2bf2

View File

@ -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");