From: Qian Cai <cai@lca.pw>
To: davem@davemloft.net
Cc: kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org, kuba@kernel.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
Qian Cai <cai@lca.pw>
Subject: [PATCH] ipv4: fix a RCU-list lock in fib_triestat_seq_show
Date: Wed, 25 Mar 2020 11:55:32 -0400 [thread overview]
Message-ID: <20200325155532.7238-1-cai@lca.pw> (raw)
fib_triestat_seq_show() calls hlist_for_each_entry_rcu(tb, head,
tb_hlist) without rcu_read_lock() will trigger a warning,
net/ipv4/fib_trie.c:2579 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 proc01/115277:
#0: c0000014507acf00 (&p->lock){+.+.}-{3:3}, at: seq_read+0x58/0x670
Call Trace:
dump_stack+0xf4/0x164 (unreliable)
lockdep_rcu_suspicious+0x140/0x164
fib_triestat_seq_show+0x750/0x880
seq_read+0x1a0/0x670
proc_reg_read+0x10c/0x1b0
__vfs_read+0x3c/0x70
vfs_read+0xac/0x170
ksys_read+0x7c/0x140
system_call+0x5c/0x68
Signed-off-by: Qian Cai <cai@lca.pw>
---
net/ipv4/fib_trie.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/ipv4/fib_trie.c b/net/ipv4/fib_trie.c
index ff0c24371e33..73fa37476f03 100644
--- a/net/ipv4/fib_trie.c
+++ b/net/ipv4/fib_trie.c
@@ -2577,6 +2577,7 @@ static int fib_triestat_seq_show(struct seq_file *seq, void *v)
" %zd bytes, size of tnode: %zd bytes.\n",
LEAF_SIZE, TNODE_SIZE(0));
+ rcu_read_lock();
for (h = 0; h < FIB_TABLE_HASHSZ; h++) {
struct hlist_head *head = &net->ipv4.fib_table_hash[h];
struct fib_table *tb;
@@ -2597,6 +2598,7 @@ static int fib_triestat_seq_show(struct seq_file *seq, void *v)
#endif
}
}
+ rcu_read_unlock();
return 0;
}
--
2.21.0 (Apple Git-122.2)
next reply other threads:[~2020-03-25 15:56 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-03-25 15:55 Qian Cai [this message]
2020-03-25 16:13 ` [PATCH] ipv4: fix a RCU-list lock in fib_triestat_seq_show Eric Dumazet
2020-03-25 17:34 ` Qian Cai
2020-03-25 18:31 ` Eric Dumazet
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