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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 CC0D2C04E53 for ; Wed, 15 May 2019 11:35:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F9922053B for ; Wed, 15 May 2019 11:35:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557920100; bh=Fsna/64TZ5f41MRSB9y1QYQgLzTM+sOs5ADmu9gRS8g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=a1N+9WLZIbTjavebi1rWeJd0/L2VRZUboa/3ywuKGnSHcB/eduQvAjuSAHuww2Rca s6rh+YIfIOXsifGMIcImudmfN+yU2hcTIHB3wB8VaXhGoJZl1bnbF3xAWQ/7acy6o4 4fplkBjQB4PAFP3HfPOa0LiekUu7j+MpCqQkTUWg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733264AbfEOLdw (ORCPT ); Wed, 15 May 2019 07:33:52 -0400 Received: from mail.kernel.org ([198.145.29.99]:45822 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732737AbfEOLdw (ORCPT ); Wed, 15 May 2019 07:33:52 -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 EEA65206BF; Wed, 15 May 2019 11:33:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1557920031; bh=Fsna/64TZ5f41MRSB9y1QYQgLzTM+sOs5ADmu9gRS8g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ynIO9k9zuL76r8zhJUrwrtCWNHmFZQSkCCUuWHUhP1EzGxEtqOaHF5XiCm6ZlPeFr zIaAih0hYHa0EY8LM7hZFJ5LeOK/0iFK5NCdjITezwTYkh+hpYRsaXAcQZXL/UZXdB Dy+TKq0lajyLSGyO+3KfhoP5gUybez3VV64ajUFQ= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Eric Dumazet , syzbot , Petar Penkov , Stanislav Fomichev , "David S. Miller" Subject: [PATCH 5.1 35/46] flow_dissector: disable preemption around BPF calls Date: Wed, 15 May 2019 12:56:59 +0200 Message-Id: <20190515090627.278573502@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190515090616.670410738@linuxfoundation.org> References: <20190515090616.670410738@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Eric Dumazet [ Upstream commit b1c17a9a353878602fd5bfe9103e4afe5e9a3f96 ] Various things in eBPF really require us to disable preemption before running an eBPF program. syzbot reported : BUG: assuming atomic context at net/core/flow_dissector.c:737 in_atomic(): 0, irqs_disabled(): 0, pid: 24710, name: syz-executor.3 2 locks held by syz-executor.3/24710: #0: 00000000e81a4bf1 (&tfile->napi_mutex){+.+.}, at: tun_get_user+0x168e/0x3ff0 drivers/net/tun.c:1850 #1: 00000000254afebd (rcu_read_lock){....}, at: __skb_flow_dissect+0x1e1/0x4bb0 net/core/flow_dissector.c:822 CPU: 1 PID: 24710 Comm: syz-executor.3 Not tainted 5.1.0+ #6 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x172/0x1f0 lib/dump_stack.c:113 __cant_sleep kernel/sched/core.c:6165 [inline] __cant_sleep.cold+0xa3/0xbb kernel/sched/core.c:6142 bpf_flow_dissect+0xfe/0x390 net/core/flow_dissector.c:737 __skb_flow_dissect+0x362/0x4bb0 net/core/flow_dissector.c:853 skb_flow_dissect_flow_keys_basic include/linux/skbuff.h:1322 [inline] skb_probe_transport_header include/linux/skbuff.h:2500 [inline] skb_probe_transport_header include/linux/skbuff.h:2493 [inline] tun_get_user+0x2cfe/0x3ff0 drivers/net/tun.c:1940 tun_chr_write_iter+0xbd/0x156 drivers/net/tun.c:2037 call_write_iter include/linux/fs.h:1872 [inline] do_iter_readv_writev+0x5fd/0x900 fs/read_write.c:693 do_iter_write fs/read_write.c:970 [inline] do_iter_write+0x184/0x610 fs/read_write.c:951 vfs_writev+0x1b3/0x2f0 fs/read_write.c:1015 do_writev+0x15b/0x330 fs/read_write.c:1058 __do_sys_writev fs/read_write.c:1131 [inline] __se_sys_writev fs/read_write.c:1128 [inline] __x64_sys_writev+0x75/0xb0 fs/read_write.c:1128 do_syscall_64+0x103/0x670 arch/x86/entry/common.c:298 entry_SYSCALL_64_after_hwframe+0x49/0xbe Fixes: d58e468b1112 ("flow_dissector: implements flow dissector BPF hook") Signed-off-by: Eric Dumazet Reported-by: syzbot Cc: Petar Penkov Cc: Stanislav Fomichev Signed-off-by: David S. Miller Signed-off-by: Greg Kroah-Hartman --- net/core/flow_dissector.c | 3 +++ 1 file changed, 3 insertions(+) --- a/net/core/flow_dissector.c +++ b/net/core/flow_dissector.c @@ -712,7 +712,10 @@ bool __skb_flow_bpf_dissect(struct bpf_p flow_keys->thoff = flow_keys->nhoff; bpf_compute_data_pointers((struct sk_buff *)skb); + + preempt_disable(); result = BPF_PROG_RUN(prog, skb); + preempt_enable(); /* Restore state */ memcpy(cb, &cb_saved, sizeof(cb_saved));