From: Vasily Averin vvs@virtuozzo.com
commit c23a9fd209bc6f8c1fa6ee303fdf037d784a1627 upstream.
Two patches listed below removed ctnetlink_dump_helpinfo call from under rcu_read_lock. Now its rcu_dereference generates following warning: ============================= WARNING: suspicious RCU usage 5.13.0+ #5 Not tainted ----------------------------- net/netfilter/nf_conntrack_netlink.c:221 suspicious rcu_dereference_check() usage!
other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 stack backtrace: CPU: 1 PID: 2251 Comm: conntrack Not tainted 5.13.0+ #5 Call Trace: dump_stack+0x7f/0xa1 ctnetlink_dump_helpinfo+0x134/0x150 [nf_conntrack_netlink] ctnetlink_fill_info+0x2c2/0x390 [nf_conntrack_netlink] ctnetlink_dump_table+0x13f/0x370 [nf_conntrack_netlink] netlink_dump+0x10c/0x370 __netlink_dump_start+0x1a7/0x260 ctnetlink_get_conntrack+0x1e5/0x250 [nf_conntrack_netlink] nfnetlink_rcv_msg+0x613/0x993 [nfnetlink] netlink_rcv_skb+0x50/0x100 nfnetlink_rcv+0x55/0x120 [nfnetlink] netlink_unicast+0x181/0x260 netlink_sendmsg+0x23f/0x460 sock_sendmsg+0x5b/0x60 __sys_sendto+0xf1/0x160 __x64_sys_sendto+0x24/0x30 do_syscall_64+0x36/0x70 entry_SYSCALL_64_after_hwframe+0x44/0xae
Fixes: 49ca022bccc5 ("netfilter: ctnetlink: don't dump ct extensions of unconfirmed conntracks") Fixes: 0b35f6031a00 ("netfilter: Remove duplicated rcu_read_lock.") Signed-off-by: Vasily Averin vvs@virtuozzo.com Reviewed-by: Florian Westphal fw@strlen.de Signed-off-by: Pablo Neira Ayuso pablo@netfilter.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/netfilter/nf_conntrack_netlink.c | 3 +++ 1 file changed, 3 insertions(+)
--- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -211,6 +211,7 @@ static int ctnetlink_dump_helpinfo(struc if (!help) return 0;
+ rcu_read_lock(); helper = rcu_dereference(help->helper); if (!helper) goto out; @@ -226,9 +227,11 @@ static int ctnetlink_dump_helpinfo(struc
nla_nest_end(skb, nest_helper); out: + rcu_read_unlock(); return 0;
nla_put_failure: + rcu_read_unlock(); return -1; }