From 3b369bd212d5cabb46cff0e863298971b382bbd6 Mon Sep 17 00:00:00 2001 From: Lennert Buytenhek Date: Thu, 28 May 2015 15:38:32 +0300 Subject: [PATCH] ieee802154: Fix generation of random EUI-64 addresses. Currently, ieee802154_random_extended_addr() has a 50% chance of generating a group (multicast) address, while this function is used for generating station addresses (which can't be group addresses) for interfaces that don't have a hardware-provided address. Also, in case get_random_bytes() generates the EUI-64 address 00:00:00:00:00:00:00:00 (extremely unlikely), which is an invalid address, ieee802154_random_extended_addr() reacts by changing it to 01:00:00:00:00:00:00:00, which is an invalid station address as well, as it is a group address. This patch changes the address generation procedure to grab eight random bytes, treat that as an EUI-64, and then clear the Group address bit and set the Locally Administered bit, which is in line with how eth_random_addr() generates random EUI-48s. Signed-off-by: Lennert Buytenhek Acked-by: Alexander Aring Signed-off-by: Marcel Holtmann --- include/linux/ieee802154.h | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/include/linux/ieee802154.h b/include/linux/ieee802154.h index 8872ca103d06..552210d0a46f 100644 --- a/include/linux/ieee802154.h +++ b/include/linux/ieee802154.h @@ -244,9 +244,9 @@ static inline void ieee802154_random_extended_addr(__le64 *addr) { get_random_bytes(addr, IEEE802154_EXTENDED_ADDR_LEN); - /* toggle some bit if we hit an invalid extended addr */ - if (!ieee802154_is_valid_extended_addr(*addr)) - ((u8 *)addr)[IEEE802154_EXTENDED_ADDR_LEN - 1] ^= 0x01; + /* clear the group bit, and set the locally administered bit */ + ((u8 *)addr)[IEEE802154_EXTENDED_ADDR_LEN - 1] &= ~0x01; + ((u8 *)addr)[IEEE802154_EXTENDED_ADDR_LEN - 1] |= 0x02; } #endif /* LINUX_IEEE802154_H */ -- 2.20.1