5.4-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet edumazet@google.com
[ 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@google.com Cc: Nicolas Dichtel nicolas.dichtel@6wind.com
Signed-off-by: Eric Dumazet edumazet@google.com Acked-by: Nicolas Dichtel nicolas.dichtel@6wind.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/addrconf.c | 21 ++++++++++++++++++--- 1 file changed, 18 insertions(+), 3 deletions(-)
diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c index 4bec4c0617412..6fcbe8912b431 100644 --- a/net/ipv6/addrconf.c +++ b/net/ipv6/addrconf.c @@ -696,6 +696,22 @@ 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) { @@ -729,8 +745,7 @@ 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; @@ -5232,7 +5247,7 @@ 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];