e1000: Avoid infinite loop in processing transmit descriptor (CVE-201…

…5-6815) 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
seanbruno · Sep 15, 2015 · b947ac2 · b947ac2
1 parent 2752e5b
commit b947ac2
Showing 1 changed file with 2 additions and 1 deletion.
diff --git 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");