Messages in this thread Patch in this message | | | From | Helge Deller <> | Subject | [PATCH 1/2] UUID: set multicast bit in pseudo-random MAC address | Date | Sat, 20 Oct 2007 21:58:40 +0200 |
| |
Fix a bug in the current random UUID generator:
Section 4.1.6 of RFC 4122 states regarding the "NodeID" of a UUID: : For systems with no IEEE address, a randomly or pseudo-randomly : generated value may be used; see Section 4.5. The multicast bit must : be set in such addresses, in order that they will never conflict with : addresses obtained from network cards.
So up to now it was just pure ("random") luck if this bit was set or not. This tiny patch sets the bit explicitely.
Signed-off-by: Helge Deller <deller@gmx.de> CC: Valdis.Kletnieks@vt.edu
random.c | 2 ++ 1 file changed, 2 insertions(+)
--- a/drivers/char/random.c +++ b/drivers/char/random.c @@ -1157,6 +1158,8 @@ void generate_random_uuid(unsigned char uuid_out[16]) uuid_out[6] = (uuid_out[6] & 0x0F) | 0x40; /* Set the UUID variant to DCE */ uuid_out[8] = (uuid_out[8] & 0x3F) | 0x80; + /* Set multicast bit to avoid conflicts with NIC MAC addresses */ + uuid_out[10] |= 0x80; } EXPORT_SYMBOL(generate_random_uuid); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |