| From c23a9fd209bc6f8c1fa6ee303fdf037d784a1627 Mon Sep 17 00:00:00 2001 |
| From: Vasily Averin <vvs@virtuozzo.com> |
| Date: Thu, 1 Jul 2021 08:02:49 +0300 |
| Subject: netfilter: ctnetlink: suspicious RCU usage in ctnetlink_dump_helpinfo |
| |
| 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 |
| @@ -213,6 +213,7 @@ static int ctnetlink_dump_helpinfo(struc |
| if (!help) |
| return 0; |
| |
| + rcu_read_lock(); |
| helper = rcu_dereference(help->helper); |
| if (!helper) |
| goto out; |
| @@ -228,9 +229,11 @@ 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; |
| } |
| |