[Qemu-devel] [PATCH] net: disallow to specify multicast MAC address

[Dmitry Krivenok <krivenok.dmitry@gmail.com>]

Added explicit check of MAC address specified via macaddr option.
Multicast MAC addresses are no longer allowed.
This fixes bug #495566.

Signed-off-by: Dmitry V. Krivenok <krivenok.dmitry@gmail.com>
---
 net/net.c  | 5 +++++
 net/util.c | 5 +++++
 net/util.h | 2 ++
 3 files changed, 12 insertions(+)

diff --git a/net/net.c b/net/net.c
index c330c9a..b3a42e5 100644
--- a/net/net.c
+++ b/net/net.c
@@ -689,6 +689,11 @@ static int net_init_nic(const NetClientOptions
*opts, const char *name,
         error_report("invalid syntax for ethernet address");
         return -1;
     }
+    if (nic->has_macaddr &&
+        net_macaddr_is_multicast(nd->macaddr.a)) {
+        error_report("NIC cannot have multicast MAC address (odd 1st byte)");
+        return -1;
+    }
     qemu_macaddr_default_if_unset(&nd->macaddr);

     if (nic->has_vectors) {
diff --git a/net/util.c b/net/util.c
index 7e95076..b86ac03 100644
--- a/net/util.c
+++ b/net/util.c
@@ -58,3 +58,8 @@ int net_parse_macaddr(uint8_t *macaddr, const char *p)

     return 0;
 }
+
+bool net_macaddr_is_multicast(uint8_t *macaddr)
+{
+    return (macaddr[0] % 2) ? true : false;
+}
diff --git a/net/util.h b/net/util.h
index 10c7da9..4581cb7 100644
--- a/net/util.h
+++ b/net/util.h
@@ -26,7 +26,9 @@
 #define QEMU_NET_UTIL_H

 #include <stdint.h>
+#include <stdbool.h>

 int net_parse_macaddr(uint8_t *macaddr, const char *p);
+bool net_macaddr_is_multicast(uint8_t *macaddr);

 #endif /* QEMU_NET_UTIL_H */
-- 
1.8.3