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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CCB85C3526F for ; Mon, 24 Jan 2022 21:28:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1452812AbiAXV0i (ORCPT ); Mon, 24 Jan 2022 16:26:38 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]:42298 "EHLO dfw.source.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1391699AbiAXUs0 (ORCPT ); Mon, 24 Jan 2022 15:48:26 -0500 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 8894B60C3F; Mon, 24 Jan 2022 20:48:24 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 649DBC340E5; Mon, 24 Jan 2022 20:48:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1643057304; bh=ekvhrQOAS/MQjky6nakGfLKJtqZG6H3R4/eM51qJ2aw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=r3l672sz0aP26sfdF2ycdeXWT/1zdhGOievPYSxiXbkoDCbfEvXY4p5hyylaaPPQy w7/YidhnBUiFQy3k3bTq3/Zf9I0lX90Df+r8Gn7iWDMx3c4UXJmExJtinvyXNrminO VkmQ+VlXuG8dPFA8edrOzXCKekIcQvGZAnBEmYAE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , syzbot , David Laight , Ido Schimmel , Jiri Pirko , Ido Schimmel , "David S. Miller" Subject: [PATCH 5.15 769/846] ipv4: update fib_info_cnt under spinlock protection Date: Mon, 24 Jan 2022 19:44:46 +0100 Message-Id: <20220124184127.491611827@linuxfoundation.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220124184100.867127425@linuxfoundation.org> References: <20220124184100.867127425@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Eric Dumazet commit 0a6e6b3c7db6c34e3d149f09cd714972f8753e3f upstream. In the past, free_fib_info() was supposed to be called under RTNL protection. This eventually was no longer the case. Instead of enforcing RTNL it seems we simply can move fib_info_cnt changes to occur when fib_info_lock is held. v2: David Laight suggested to update fib_info_cnt only when an entry is added/deleted to/from the hash table, as fib_info_cnt is used to make sure hash table size is optimal. BUG: KCSAN: data-race in fib_create_info / free_fib_info write to 0xffffffff86e243a0 of 4 bytes by task 26429 on cpu 0: fib_create_info+0xe78/0x3440 net/ipv4/fib_semantics.c:1428 fib_table_insert+0x148/0x10c0 net/ipv4/fib_trie.c:1224 fib_magic+0x195/0x1e0 net/ipv4/fib_frontend.c:1087 fib_add_ifaddr+0xd0/0x2e0 net/ipv4/fib_frontend.c:1109 fib_netdev_event+0x178/0x510 net/ipv4/fib_frontend.c:1466 notifier_call_chain kernel/notifier.c:83 [inline] raw_notifier_call_chain+0x53/0xb0 kernel/notifier.c:391 __dev_notify_flags+0x1d3/0x3b0 dev_change_flags+0xa2/0xc0 net/core/dev.c:8872 do_setlink+0x810/0x2410 net/core/rtnetlink.c:2719 rtnl_group_changelink net/core/rtnetlink.c:3242 [inline] __rtnl_newlink net/core/rtnetlink.c:3396 [inline] rtnl_newlink+0xb10/0x13b0 net/core/rtnetlink.c:3506 rtnetlink_rcv_msg+0x745/0x7e0 net/core/rtnetlink.c:5571 netlink_rcv_skb+0x14e/0x250 net/netlink/af_netlink.c:2496 rtnetlink_rcv+0x18/0x20 net/core/rtnetlink.c:5589 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x5fc/0x6c0 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x726/0x840 net/netlink/af_netlink.c:1921 sock_sendmsg_nosec net/socket.c:704 [inline] sock_sendmsg net/socket.c:724 [inline] ____sys_sendmsg+0x39a/0x510 net/socket.c:2409 ___sys_sendmsg net/socket.c:2463 [inline] __sys_sendmsg+0x195/0x230 net/socket.c:2492 __do_sys_sendmsg net/socket.c:2501 [inline] __se_sys_sendmsg net/socket.c:2499 [inline] __x64_sys_sendmsg+0x42/0x50 net/socket.c:2499 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x44/0xd0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae read to 0xffffffff86e243a0 of 4 bytes by task 31505 on cpu 1: free_fib_info+0x35/0x80 net/ipv4/fib_semantics.c:252 fib_info_put include/net/ip_fib.h:575 [inline] nsim_fib4_rt_destroy drivers/net/netdevsim/fib.c:294 [inline] nsim_fib4_rt_replace drivers/net/netdevsim/fib.c:403 [inline] nsim_fib4_rt_insert drivers/net/netdevsim/fib.c:431 [inline] nsim_fib4_event drivers/net/netdevsim/fib.c:461 [inline] nsim_fib_event drivers/net/netdevsim/fib.c:881 [inline] nsim_fib_event_work+0x15ca/0x2cf0 drivers/net/netdevsim/fib.c:1477 process_one_work+0x3fc/0x980 kernel/workqueue.c:2298 process_scheduled_works kernel/workqueue.c:2361 [inline] worker_thread+0x7df/0xa70 kernel/workqueue.c:2447 kthread+0x2c7/0x2e0 kernel/kthread.c:327 ret_from_fork+0x1f/0x30 value changed: 0x00000d2d -> 0x00000d2e Reported by Kernel Concurrency Sanitizer on: CPU: 1 PID: 31505 Comm: kworker/1:21 Not tainted 5.16.0-rc6-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Workqueue: events nsim_fib_event_work Fixes: 48bb9eb47b27 ("netdevsim: fib: Add dummy implementation for FIB offload") Signed-off-by: Eric Dumazet Reported-by: syzbot Cc: David Laight Cc: Ido Schimmel Cc: Jiri Pirko Reviewed-by: Ido Schimmel Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/ipv4/fib_semantics.c | 11 ++++++++--- 1 file changed, 8 insertions(+), 3 deletions(-) --- a/net/ipv4/fib_semantics.c +++ b/net/ipv4/fib_semantics.c @@ -249,7 +249,6 @@ void free_fib_info(struct fib_info *fi) pr_warn("Freeing alive fib_info %p\n", fi); return; } - fib_info_cnt--; call_rcu(&fi->rcu, free_fib_info_rcu); } @@ -260,6 +259,10 @@ void fib_release_info(struct fib_info *f spin_lock_bh(&fib_info_lock); if (fi && refcount_dec_and_test(&fi->fib_treeref)) { hlist_del(&fi->fib_hash); + + /* Paired with READ_ONCE() in fib_create_info(). */ + WRITE_ONCE(fib_info_cnt, fib_info_cnt - 1); + if (fi->fib_prefsrc) hlist_del(&fi->fib_lhash); if (fi->nh) { @@ -1430,7 +1433,9 @@ struct fib_info *fib_create_info(struct #endif err = -ENOBUFS; - if (fib_info_cnt >= fib_info_hash_size) { + + /* Paired with WRITE_ONCE() in fib_release_info() */ + if (READ_ONCE(fib_info_cnt) >= fib_info_hash_size) { unsigned int new_size = fib_info_hash_size << 1; struct hlist_head *new_info_hash; struct hlist_head *new_laddrhash; @@ -1462,7 +1467,6 @@ struct fib_info *fib_create_info(struct return ERR_PTR(err); } - fib_info_cnt++; fi->fib_net = net; fi->fib_protocol = cfg->fc_protocol; fi->fib_scope = cfg->fc_scope; @@ -1589,6 +1593,7 @@ link_it: refcount_set(&fi->fib_treeref, 1); refcount_set(&fi->fib_clntref, 1); spin_lock_bh(&fib_info_lock); + fib_info_cnt++; hlist_add_head(&fi->fib_hash, &fib_info_hash[fib_info_hashfn(fi)]); if (fi->fib_prefsrc) {