Messages in this thread | | | Subject | Re: [PATCH] ipv4: fix a RCU-list bug in inet_dump_fib() | From | David Ahern <> | Date | Thu, 19 Mar 2020 16:32:15 -0600 |
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On 3/19/20 4:11 PM, Qian Cai wrote: > There is a place, > > inet_dump_fib() > fib_table_dump > fn_trie_dump_leaf() > hlist_for_each_entry_rcu() > > without rcu_read_lock() triggers a warning, > > WARNING: suspicious RCU usage > ----------------------------- > net/ipv4/fib_trie.c:2216 RCU-list traversed in non-reader section!! > > other info that might help us debug this: > > rcu_scheduler_active = 2, debug_locks = 1 > 1 lock held by ip/1923: > #0: ffffffff8ce76e40 (rtnl_mutex){+.+.}, at: netlink_dump+0xd6/0x840 > > Call Trace: > dump_stack+0xa1/0xea > lockdep_rcu_suspicious+0x103/0x10d > fn_trie_dump_leaf+0x581/0x590 > fib_table_dump+0x15f/0x220 > inet_dump_fib+0x4ad/0x5d0 > netlink_dump+0x350/0x840 > __netlink_dump_start+0x315/0x3e0 > rtnetlink_rcv_msg+0x4d1/0x720 > netlink_rcv_skb+0xf0/0x220 > rtnetlink_rcv+0x15/0x20 > netlink_unicast+0x306/0x460 > netlink_sendmsg+0x44b/0x770 > __sys_sendto+0x259/0x270 > __x64_sys_sendto+0x80/0xa0 > do_syscall_64+0x69/0xf4 > entry_SYSCALL_64_after_hwframe+0x49/0xb3 >
Fixes: 18a8021a7be3 ("net/ipv4: Plumb support for filtering route dumps")
but you have a problem below ...
> Signed-off-by: Qian Cai <cai@lca.pw> > --- > net/ipv4/fib_frontend.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/ipv4/fib_frontend.c b/net/ipv4/fib_frontend.c > index 577db1d50a24..5e441282d647 100644 > --- a/net/ipv4/fib_frontend.c > +++ b/net/ipv4/fib_frontend.c > @@ -987,6 +987,8 @@ static int inet_dump_fib(struct sk_buff *skb, struct netlink_callback *cb) > if (filter.flags & RTM_F_PREFIX) > return skb->len; > > + rcu_read_lock(); > + > if (filter.table_id) { > tb = fib_get_table(net, filter.table_id); > if (!tb) {
this branch has 2 return points which now have rcu_read_lock; you should have seen this when you tested the change..
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