From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 80D85B676; Mon, 23 Jun 2025 22:28:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750717710; cv=none; b=lR8p0kAVPHwgO2zQExj/1nJOt4hbybuta4TV/kdAsPZM3orZx1uP7Bnraj5jvtU88GDHGOE5p800YdmZu25DpdzZWBzEY5ZC4UmQgeDUXfnOWLvLJ7qtsE4SXjAKGRBHgHw/1PY+A9+6EtcFCnJSAvznfATZXbuToXhtZi5UXsk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750717710; c=relaxed/simple; bh=EZ54n3aLudQfASNTvu/xADx8OwyTd1Tirbb94NWX20U=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mHeYtnbrXuoZQKPMjEeYaGaNYCi3xcu9dXjkVEVMG2nCLaWvIOEMLZceCP3gABx3wL6B67Oat7C62fC9OURPmx6fVs53eiZLXiNCcxkJDNdy2TVHpMVgM+ITVDviPUdrVt6skdqerkRfmdQVlZCvWbyl/VIBkDHd58QtCDzj5ts= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=U5e9ld5A; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="U5e9ld5A" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1B0C5C4CEEA; Mon, 23 Jun 2025 22:28:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1750717710; bh=EZ54n3aLudQfASNTvu/xADx8OwyTd1Tirbb94NWX20U=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=U5e9ld5A1I5DNFntO37D3u75+s335b7esC05UiZWzT7+Gt1mjZPkap4fYqGrszt0M obpyRg0ommirMCOsWToEOSrmlia4jwAZ1Jhp0eAWvvXOXTaZluXDmXNJOekXjCFwCY pkPIsuuz6tOoBF/+RdFoi/MhsXDmQW/muJ/JtkkQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+8a583bdd1a5cc0b0e068@syzkaller.appspotmail.com, Kuniyuki Iwashima , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.1 482/508] mpls: Use rcu_dereference_rtnl() in mpls_route_input_rcu(). Date: Mon, 23 Jun 2025 15:08:47 +0200 Message-ID: <20250623130656.924242720@linuxfoundation.org> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250623130645.255320792@linuxfoundation.org> References: <20250623130645.255320792@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kuniyuki Iwashima [ Upstream commit 6dbb0d97c5096072c78a6abffe393584e57ae945 ] As syzbot reported [0], mpls_route_input_rcu() can be called from mpls_getroute(), where is under RTNL. net->mpls.platform_label is only updated under RTNL. Let's use rcu_dereference_rtnl() in mpls_route_input_rcu() to silence the splat. [0]: WARNING: suspicious RCU usage 6.15.0-rc7-syzkaller-00082-g5cdb2c77c4c3 #0 Not tainted ---------------------------- net/mpls/af_mpls.c:84 suspicious rcu_dereference_check() usage! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by syz.2.4451/17730: #0: ffffffff9012a3e8 (rtnl_mutex){+.+.}-{4:4}, at: rtnl_lock net/core/rtnetlink.c:80 [inline] #0: ffffffff9012a3e8 (rtnl_mutex){+.+.}-{4:4}, at: rtnetlink_rcv_msg+0x371/0xe90 net/core/rtnetlink.c:6961 stack backtrace: CPU: 1 UID: 0 PID: 17730 Comm: syz.2.4451 Not tainted 6.15.0-rc7-syzkaller-00082-g5cdb2c77c4c3 #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 Call Trace: __dump_stack lib/dump_stack.c:94 [inline] dump_stack_lvl+0x16c/0x1f0 lib/dump_stack.c:120 lockdep_rcu_suspicious+0x166/0x260 kernel/locking/lockdep.c:6865 mpls_route_input_rcu+0x1d4/0x200 net/mpls/af_mpls.c:84 mpls_getroute+0x621/0x1ea0 net/mpls/af_mpls.c:2381 rtnetlink_rcv_msg+0x3c9/0xe90 net/core/rtnetlink.c:6964 netlink_rcv_skb+0x16d/0x440 net/netlink/af_netlink.c:2534 netlink_unicast_kernel net/netlink/af_netlink.c:1313 [inline] netlink_unicast+0x53a/0x7f0 net/netlink/af_netlink.c:1339 netlink_sendmsg+0x8d1/0xdd0 net/netlink/af_netlink.c:1883 sock_sendmsg_nosec net/socket.c:712 [inline] __sock_sendmsg net/socket.c:727 [inline] ____sys_sendmsg+0xa98/0xc70 net/socket.c:2566 ___sys_sendmsg+0x134/0x1d0 net/socket.c:2620 __sys_sendmmsg+0x200/0x420 net/socket.c:2709 __do_sys_sendmmsg net/socket.c:2736 [inline] __se_sys_sendmmsg net/socket.c:2733 [inline] __x64_sys_sendmmsg+0x9c/0x100 net/socket.c:2733 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f0a2818e969 Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f0a28f52038 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f0a283b5fa0 RCX: 00007f0a2818e969 RDX: 0000000000000003 RSI: 0000200000000080 RDI: 0000000000000003 RBP: 00007f0a28210ab1 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 0000000000000000 R14: 00007f0a283b5fa0 R15: 00007ffce5e9f268 Fixes: 0189197f4416 ("mpls: Basic routing support") Reported-by: syzbot+8a583bdd1a5cc0b0e068@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/68507981.a70a0220.395abc.01ef.GAE@google.com/ Signed-off-by: Kuniyuki Iwashima Link: https://patch.msgid.link/20250616201532.1036568-1-kuni1840@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/mpls/af_mpls.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/mpls/af_mpls.c b/net/mpls/af_mpls.c index f1f43894efb8e..2d29d230f5698 100644 --- a/net/mpls/af_mpls.c +++ b/net/mpls/af_mpls.c @@ -80,8 +80,8 @@ static struct mpls_route *mpls_route_input_rcu(struct net *net, unsigned index) if (index < net->mpls.platform_labels) { struct mpls_route __rcu **platform_label = - rcu_dereference(net->mpls.platform_label); - rt = rcu_dereference(platform_label[index]); + rcu_dereference_rtnl(net->mpls.platform_label); + rt = rcu_dereference_rtnl(platform_label[index]); } return rt; } -- 2.39.5