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;
+}