From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0FEF8C2BA2B for ; Sat, 11 Apr 2020 12:10:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D6BB621655 for ; Sat, 11 Apr 2020 12:10:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586607046; bh=ZhPfXwdhyzdj32voEjkcU8CfMlM/xNaQVegWyaKUHX4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=QhnIIKUa95KCCG2/iL8gELbVTUT96m14AO1zvW3BTnLZ/9Z+er+KsCoSxzz0IEroN 2QfC+GN7cpWeyliHYc/6kmkq2cZAEJRZ/rk9Qi3YfMRcuciLGq2VIovbAhDOmveIMb Sfb52BQ1au189t2wtxo+lUmRvXcANiGghCBIjW1U= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726687AbgDKMKl (ORCPT ); Sat, 11 Apr 2020 08:10:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:42246 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726091AbgDKMKk (ORCPT ); Sat, 11 Apr 2020 08:10:40 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id CCCA02084D; Sat, 11 Apr 2020 12:10:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1586607039; bh=ZhPfXwdhyzdj32voEjkcU8CfMlM/xNaQVegWyaKUHX4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=F654Ntsv1baM+3XxpHOvJ6zq14VeBtPcfAJQSqZY95fb9bolGJ42K3Nl6yfGnLnE5 fgAirp8oIYzOs2fehwZxa6OeDYacTBs8rngUj1OIFnpTK97aCO1GMvzoKs6HNcpCU9 n9RmPTkUphT3Pgfg1kr0PwleBlLm1PZWf+NDU+VY= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Qian Cai , Eric Dumazet , "David S. Miller" Subject: [PATCH 4.4 02/29] ipv4: fix a RCU-list lock in fib_triestat_seq_show Date: Sat, 11 Apr 2020 14:08:32 +0200 Message-Id: <20200411115407.957243103@linuxfoundation.org> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200411115407.651296755@linuxfoundation.org> References: <20200411115407.651296755@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Qian Cai [ Upstream commit fbe4e0c1b298b4665ee6915266c9d6c5b934ef4a ] 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 Fix it by adding a pair of rcu_read_lock/unlock() and use cond_resched_rcu() to avoid the situation where walking of a large number of items may prevent scheduling for a long time. Signed-off-by: Qian Cai Reviewed-by: Eric Dumazet Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/fib_trie.c | 3 +++ 1 file changed, 3 insertions(+) --- a/net/ipv4/fib_trie.c +++ b/net/ipv4/fib_trie.c @@ -2230,6 +2230,7 @@ static int fib_triestat_seq_show(struct " %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; @@ -2249,7 +2250,9 @@ static int fib_triestat_seq_show(struct trie_show_usage(seq, t->stats); #endif } + cond_resched_rcu(); } + rcu_read_unlock(); return 0; }