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ipv6/addrconf: ensure addrconf_verify_rtnl() has completed

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Before freeing the hash table in addrconf_exit_net(),
we need to make sure the work queue has completed,
or risk NULL dereference or UAF.

Thus, use cancel_delayed_work_sync() to enforce this.
We do not hold RTNL in addrconf_exit_net(), making this safe.

Fixes: 8805d13ff1 ("ipv6/addrconf: use one delayed work per netns")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: syzbot <syzkaller@googlegroups.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20220216182037.3742-1-eric.dumazet@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2022-02-16 10:20:37 -08:00 committed by Jakub Kicinski
parent faab39f63c
commit be6b41c15d
1 changed files with 1 additions and 1 deletions
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2
net/ipv6/addrconf.c
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@ -7187,7 +7187,7 @@ static void __net_exit addrconf_exit_net(struct net *net)
kfree(net->ipv6.devconf_all);
net->ipv6.devconf_all = NULL;
cancel_delayed_work(&net->ipv6.addr_chk_work);
cancel_delayed_work_sync(&net->ipv6.addr_chk_work);
/*
* Check hash table, then free it.
*/