2 files changed, 41 insertions, 4 deletions

diff --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c
index bd1178fa4e9a..684a1ef93c87 100644
--- a/arch/um/drivers/net_kern.c
+++ b/arch/um/drivers/net_kern.c
@@ -753,7 +753,8 @@ int setup_etheraddr(char *str, unsigned char *addr)
         int i;
 
         if(str == NULL)
-                return(0);
+                goto random;
+
         for(i=0;i<6;i++){
                 addr[i] = simple_strtoul(str, &end, 16);
                 if((end == str) ||
@@ -761,7 +762,7 @@ int setup_etheraddr(char *str, unsigned char *addr)
                         printk(KERN_ERR 
                                "setup_etheraddr: failed to parse '%s' "
                                "as an ethernet address\n", str);
-                        return(0);
+                        goto random;
                 }
                 str = end + 1;
         }
@@ -769,9 +770,15 @@ int setup_etheraddr(char *str, unsigned char *addr)
                 printk(KERN_ERR 
                        "Attempt to assign a broadcast ethernet address to a "
                        "device disallowed\n");
-                return(0);
+                goto random;
         }
-        return(1);
+        return 1;
+
+random:
+        addr[0] = 0xfe;
+        addr[1] = 0xfd;
+        random_mac(addr);
+        return 1;
 }
 
 void dev_ip_addr(void *d, unsigned char *bin_buf)
diff --git a/arch/um/drivers/net_user.c b/arch/um/drivers/net_user.c
index 107c5e43fa00..142bcb2c7c6a 100644
--- a/arch/um/drivers/net_user.c
+++ b/arch/um/drivers/net_user.c
@@ -12,6 +12,7 @@
 #include <string.h>
 #include <sys/socket.h>
 #include <sys/wait.h>
+#include <sys/time.h>
 #include "user.h"
 #include "user_util.h"
 #include "kern_util.h"
@@ -258,3 +259,32 @@ char *split_if_spec(char *str, ...)
         va_end(ap);
         return str;
 }
+
+void random_mac(unsigned char *addr)
+{
+        struct timeval tv;
+        long n;
+        unsigned int seed;
+
+        gettimeofday(&tv, NULL);
+
+        /* Assume that 20 bits of microseconds and 12 bits of the pid are
+         * reasonably unpredictable.
+         */
+        seed = tv.tv_usec | (os_getpid() << 20);
+        srandom(seed);
+
+        /* Don't care about endianness here - switching endianness
+         * just rearranges what are hopefully random numbers.
+         *
+         * Assume that RAND_MAX > 65536, so random is called twice and
+         * we use 16 bits of the result.
+         */
+        n = random();
+        addr[2] = (n >> 8) & 255;
+        addr[3] = n % 255;
+
+        n = random();
+        addr[4] = (n >> 8) & 255;
+        addr[5] = n % 255;
+}