This is a note to let you know that I've just added the patch titled ipv6: properly combine dev_base_seq and ipv6.dev_addr_genid to the 6.1-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: ipv6-properly-combine-dev_base_seq-and-ipv6.dev_addr.patch and it can be found in the queue-6.1 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit f7da708e69d9514808bbbbb16d619d6054f75118 Author: Eric Dumazet <edumazet@xxxxxxxxxx> Date: Thu Feb 15 17:21:07 2024 +0000 ipv6: properly combine dev_base_seq and ipv6.dev_addr_genid [ Upstream commit e898e4cd1aab271ca414f9ac6e08e4c761f6913c ] net->dev_base_seq and ipv6.dev_addr_genid are monotonically increasing. If we XOR their values, we could miss to detect if both values were changed with the same amount. Fixes: 63998ac24f83 ("ipv6: provide addr and netconf dump consistency info") Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> Cc: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> Acked-by: Nicolas Dichtel <nicolas.dichtel@xxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index b8dc20fe7a4e2..46527b5cc8f0c 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -706,6 +706,22 @@ static int inet6_netconf_get_devconf(struct sk_buff *in_skb, return err; } +/* Combine dev_addr_genid and dev_base_seq to detect changes. + */ +static u32 inet6_base_seq(const struct net *net) +{ + u32 res = atomic_read(&net->ipv6.dev_addr_genid) + + net->dev_base_seq; + + /* Must not return 0 (see nl_dump_check_consistent()). + * Chose a value far away from 0. + */ + if (!res) + res = 0x80000000; + return res; +} + + static int inet6_netconf_dump_devconf(struct sk_buff *skb, struct netlink_callback *cb) { @@ -739,8 +755,7 @@ static int inet6_netconf_dump_devconf(struct sk_buff *skb, idx = 0; head = &net->dev_index_head[h]; rcu_read_lock(); - cb->seq = atomic_read(&net->ipv6.dev_addr_genid) ^ - net->dev_base_seq; + cb->seq = inet6_base_seq(net); hlist_for_each_entry_rcu(dev, head, index_hlist) { if (idx < s_idx) goto cont; @@ -5326,7 +5341,7 @@ static int inet6_dump_addr(struct sk_buff *skb, struct netlink_callback *cb, } rcu_read_lock(); - cb->seq = atomic_read(&tgt_net->ipv6.dev_addr_genid) ^ tgt_net->dev_base_seq; + cb->seq = inet6_base_seq(tgt_net); for (h = s_h; h < NETDEV_HASHENTRIES; h++, s_idx = 0) { idx = 0; head = &tgt_net->dev_index_head[h];