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=-9.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT 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 0F6C3C43381 for ; Fri, 15 Feb 2019 03:08:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B505A21934 for ; Fri, 15 Feb 2019 03:08:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="TJY61Pec" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727521AbfBODId (ORCPT ); Thu, 14 Feb 2019 22:08:33 -0500 Received: from mail-pg1-f194.google.com ([209.85.215.194]:41791 "EHLO mail-pg1-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726010AbfBODIc (ORCPT ); Thu, 14 Feb 2019 22:08:32 -0500 Received: by mail-pg1-f194.google.com with SMTP id m1so4086004pgq.8 for ; Thu, 14 Feb 2019 19:08:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=Gm5lzhOqxg2ffDBARrfvcJaxxv+3ujqNqdXoB3LxQmU=; b=TJY61PecfYP448k+Cr4AZTGFuU58CkG7pghKuV+bp9EYVDshior52r9rRscz17uSYZ 5V78qTWbCy8H0Mt8Sdyk5dCXS2vDVaySyF9WoUto+kfhuml1r4mydWhQ/gHQp7L2qyfe 26YfOXJc9D4Bgtbfm1WzUvWvdEy/w3Sw4J4fc+KjWqk+NuXwqu3B4MacqZDtBchZUdv/ /QbM5Dqxtg8QvPgAao0SuZZG4Fic4TgUzHCGComboCsNBbUPDDvKum3Oc1E51CSvXWzN ZulwKr96QcacB2bVcByiRrVJ9enMslMkOgbofka+8RTVV30p6/M7lBmI0tmoSOwqe+/y HbCg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=Gm5lzhOqxg2ffDBARrfvcJaxxv+3ujqNqdXoB3LxQmU=; b=BglGKc5m0SDWiKNjKwhiDkKWrLmrmb4+z6S/ch+1fwpMO3RSr04vfUwuUTJRKFl9Sc tCKFwsXAgOR50KrDEZ11emyD/sQSZRjlUD9IEtKE8czwfZyrtsoe6H+E6VPeZYAD8OFS oVFEd+eLo4CRQyOzimjA2Fes6LgxHz8glUSpCNA2oD9bfGP/GMBkUPHyFO9tDksZ3PLA W058fnyr3slQFgcags9vDviAUTPMtAODX2wmcz8FQte+Po3iaY350u/0dOpvVuFdrg8p /pANPsDb3BVjPvw6E/2MFtzE/LWNXOjGiQ84mAJP6AFYM478nXvfzewtyaEsMihGC9mu 9dxQ== X-Gm-Message-State: AHQUAuZN3JmCHhlkDqqIviwFRPE27QaLIiYFsQTQyfulDzTFu67Ptkw3 ekjJkTJZBog5hV2BetggGkM= X-Google-Smtp-Source: AHgI3IajFgvOnoTbATmNQ1p77k4hiwT+hMof+qhWQzcvg9tl27jSzSDS6/kncHyqg7t8yNwqW5lQ1w== X-Received: by 2002:a65:490e:: with SMTP id p14mr3195724pgs.373.1550200111585; Thu, 14 Feb 2019 19:08:31 -0800 (PST) Received: from ast-mbp ([2620:10d:c090:180::1:b114]) by smtp.gmail.com with ESMTPSA id z67sm6734498pfd.188.2019.02.14.19.08.29 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 14 Feb 2019 19:08:30 -0800 (PST) Date: Thu, 14 Feb 2019 19:08:27 -0800 From: Alexei Starovoitov To: Alan Maguire Cc: Naresh Kamboju , Netdev , "David S. Miller" , Valdis Kletnieks , Song Liu , Rafael Tinoco , ast@kernel.org, Daniel Borkmann Subject: Re: bpf: test_tunnel.sh: BUG: unable to handle kernel NULL pointer dereference Message-ID: <20190215030825.syexq6vfxemooyno@ast-mbp> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20180223 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Mon, Feb 11, 2019 at 04:39:50PM +0000, Alan Maguire wrote: > On Fri, 1 Feb 2019, Naresh Kamboju wrote: > > > Kernel panic while running bpf: test_tunnel.sh on linux -next > > 5.0.0-rc4-next-20190129. > > > > selftests: bpf: test_tunnel.sh > > [ 273.997647] IPv6: ADDRCONF(NETDEV_CHANGE): veth1: link becomes ready > > [ 274.054068] ip (11458) used greatest stack depth: 11448 bytes left > > [ 274.120445] BUG: unable to handle kernel NULL pointer dereference > > at 0000000000000000 > > [ 274.128285] #PF error: [INSTR] > > [ 274.131351] PGD 8000000414a0e067 P4D 8000000414a0e067 PUD 3b6334067 PMD 0 > > [ 274.138241] Oops: 0010 [#1] SMP PTI > > [ 274.141734] CPU: 1 PID: 11464 Comm: ping Not tainted > > 5.0.0-rc4-next-20190129 #1 > > [ 274.149046] Hardware name: Supermicro SYS-5019S-ML/X11SSH-F, BIOS > > 2.0b 07/27/2017 > > [ 274.156526] RIP: 0010: (null) > > [ 274.160280] Code: Bad RIP value. > > [ 274.163509] RSP: 0018:ffffbc9681f83540 EFLAGS: 00010286 > > [ 274.168726] RAX: 0000000000000000 RBX: ffffdc967fa80a18 RCX: 0000000000000000 > > [ 274.175851] RDX: ffff9db2ee08b540 RSI: 000000000000000e RDI: ffffdc967fa809a0 > > [ 274.182974] RBP: ffffbc9681f83580 R08: ffff9db2c4d62690 R09: 000000000000000c > > [ 274.190098] R10: 0000000000000000 R11: ffff9db2ee08b540 R12: ffff9db31ce7c000 > > [ 274.197222] R13: 0000000000000001 R14: 000000000000000c R15: ffff9db3179cf400 > > [ 274.204346] FS: 00007ff4ae7c5740(0000) GS:ffff9db31fa80000(0000) > > knlGS:0000000000000000 > > [ 274.212424] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 274.218162] CR2: ffffffffffffffd6 CR3: 00000004574da004 CR4: 00000000003606e0 > > [ 274.225292] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > [ 274.232416] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > [ 274.239541] Call Trace: > > [ 274.241988] ? tnl_update_pmtu+0x296/0x3b0 > > [ 274.246085] ip_md_tunnel_xmit+0x1bc/0x520 > > [ 274.250176] gre_fb_xmit+0x330/0x390 > > [ 274.253754] gre_tap_xmit+0x128/0x180 > > [ 274.257414] dev_hard_start_xmit+0xb7/0x300 > > [ 274.261598] sch_direct_xmit+0xf6/0x290 > > [ 274.265430] __qdisc_run+0x15d/0x5e0 > > [ 274.269007] __dev_queue_xmit+0x2c5/0xc00 > > [ 274.273011] ? dev_queue_xmit+0x10/0x20 > > [ 274.276842] ? eth_header+0x2b/0xc0 > > [ 274.280326] dev_queue_xmit+0x10/0x20 > > [ 274.283984] ? dev_queue_xmit+0x10/0x20 > > [ 274.287813] arp_xmit+0x1a/0xf0 > > [ 274.290952] arp_send_dst.part.19+0x46/0x60 > > [ 274.295138] arp_solicit+0x177/0x6b0 > > [ 274.298708] ? mod_timer+0x18e/0x440 > > [ 274.302281] neigh_probe+0x57/0x70 > > [ 274.305684] __neigh_event_send+0x197/0x2d0 > > [ 274.309862] neigh_resolve_output+0x18c/0x210 > > [ 274.314212] ip_finish_output2+0x257/0x690 > > [ 274.318304] ip_finish_output+0x219/0x340 > > [ 274.322314] ? ip_finish_output+0x219/0x340 > > [ 274.326493] ip_output+0x76/0x240 > > [ 274.329805] ? ip_fragment.constprop.53+0x80/0x80 > > [ 274.334510] ip_local_out+0x3f/0x70 > > [ 274.337992] ip_send_skb+0x19/0x40 > > [ 274.341391] ip_push_pending_frames+0x33/0x40 > > [ 274.345740] raw_sendmsg+0xc15/0x11d0 > > [ 274.349403] ? __might_fault+0x85/0x90 > > [ 274.353151] ? _copy_from_user+0x6b/0xa0 > > [ 274.357070] ? rw_copy_check_uvector+0x54/0x130 > > [ 274.361604] inet_sendmsg+0x42/0x1c0 > > [ 274.365179] ? inet_sendmsg+0x42/0x1c0 > > [ 274.368937] sock_sendmsg+0x3e/0x50 > > [ 274.372460] ___sys_sendmsg+0x26f/0x2d0 > > [ 274.376293] ? lock_acquire+0x95/0x190 > > [ 274.380043] ? __handle_mm_fault+0x7ce/0xb70 > > [ 274.384307] ? lock_acquire+0x95/0x190 > > [ 274.388053] ? __audit_syscall_entry+0xdd/0x130 > > [ 274.392586] ? ktime_get_coarse_real_ts64+0x64/0xc0 > > [ 274.397461] ? __audit_syscall_entry+0xdd/0x130 > > [ 274.401989] ? trace_hardirqs_on+0x4c/0x100 > > [ 274.406173] __sys_sendmsg+0x63/0xa0 > > [ 274.409744] ? __sys_sendmsg+0x63/0xa0 > > [ 274.413488] __x64_sys_sendmsg+0x1f/0x30 > > [ 274.417405] do_syscall_64+0x55/0x190 > > [ 274.421064] entry_SYSCALL_64_after_hwframe+0x49/0xbe > > [ 274.426113] RIP: 0033:0x7ff4ae0e6e87 > > [ 274.429686] Code: 64 89 02 48 c7 c0 ff ff ff ff eb b9 0f 1f 80 00 > > 00 00 00 8b 05 ca d9 2b 00 48 63 d2 48 63 ff 85 c0 75 10 b8 2e 00 00 > > 00 0f 05 <48> 3d 00 f0 ff ff 77 51 c3 53 48 89 f3 48 83 ec 10 48 89 7c > > 24 08 > > [ 274.448422] RSP: 002b:00007ffcd9b76db8 EFLAGS: 00000246 ORIG_RAX: > > 000000000000002e > > [ 274.455978] RAX: ffffffffffffffda RBX: 0000000000000040 RCX: 00007ff4ae0e6e87 > > [ 274.463104] RDX: 0000000000000000 RSI: 00000000006092e0 RDI: 0000000000000003 > > [ 274.470228] RBP: 0000000000000000 R08: 00007ffcd9bc40a0 R09: 00007ffcd9bc4080 > > [ 274.477349] R10: 000000000000060a R11: 0000000000000246 R12: 0000000000000003 > > [ 274.484475] R13: 0000000000000016 R14: 00007ffcd9b77fa0 R15: 00007ffcd9b78da4 > > [ 274.491602] Modules linked in: cls_bpf sch_ingress iptable_filter > > ip_tables algif_hash af_alg x86_pkg_temp_thermal fuse [last unloaded: > > test_bpf] > > [ 274.504634] CR2: 0000000000000000 > > [ 274.507976] ---[ end trace 196d18386545eae1 ]--- > > [ 274.512588] RIP: 0010: (null) > > [ 274.516334] Code: Bad RIP value. > > [ 274.519557] RSP: 0018:ffffbc9681f83540 EFLAGS: 00010286 > > [ 274.524775] RAX: 0000000000000000 RBX: ffffdc967fa80a18 RCX: 0000000000000000 > > [ 274.531921] RDX: ffff9db2ee08b540 RSI: 000000000000000e RDI: ffffdc967fa809a0 > > [ 274.539082] RBP: ffffbc9681f83580 R08: ffff9db2c4d62690 R09: 000000000000000c > > [ 274.546205] R10: 0000000000000000 R11: ffff9db2ee08b540 R12: ffff9db31ce7c000 > > [ 274.553329] R13: 0000000000000001 R14: 000000000000000c R15: ffff9db3179cf400 > > [ 274.560456] FS: 00007ff4ae7c5740(0000) GS:ffff9db31fa80000(0000) > > knlGS:0000000000000000 > > [ 274.568541] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 274.574277] CR2: ffffffffffffffd6 CR3: 00000004574da004 CR4: 00000000003606e0 > > [ 274.581403] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > [ 274.588535] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > [ 274.595658] Kernel panic - not syncing: Fatal exception in interrupt > > [ 274.602046] Kernel Offset: 0x14400000 from 0xffffffff81000000 > > (relocation range: 0xffffffff80000000-0xffffffffbfffffff) > > [ 274.612827] ---[ end Kernel panic - not syncing: Fatal exception in > > interrupt ]--- > > [ 274.620387] ------------[ cut here ]------------ > > > > The above log is from x86_64 device. > > > > > I'm also seeing the same panic during test_tunnel.sh execution > on x86_64. > > From poking around it looks like the skb's dst entry is being used > to calculate the mtu in: > > mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu; > > ...but because that dst_entry has an "ops" value set to md_dst_ops, > the various ops (including mtu) are not set: > > crash> struct sk_buff._skb_refdst ffff928f87447700 -x > _skb_refdst = 0xffffcd6fbf5ea590 > crash> struct dst_entry.ops 0xffffcd6fbf5ea590 > ops = 0xffffffffa0193800 > crash> struct dst_ops.mtu 0xffffffffa0193800 > mtu = 0x0 > crash> > > I confirmed that the dst entry also has dst->input set to > dst_md_discard, so it looks like it's an entry that's been > initialized via __metadata_dst_init alright. > > I think the fix here is to use skb_valid_dst(skb) - it checks > for DST_METADATA also, and with that fix in place, the > problem - which was previously 100% reproducible - disappears. The fix looks good to me. Could you please resend the patch officially? > However what we should do in terms of path MTU setting for > such cases (use ip*_update_pmtu() perhaps?), I'm not sure. > > The below patch resolves the panic and all tunnel tests pass > without incident. > > Fixes: c8b34e680a09 ("ip_tunnel: Add tnl_update_pmtu in ip_md_tunnel_xmit") > > Signed-off-by: Alan Maguire > --- > net/ipv4/ip_tunnel.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/net/ipv4/ip_tunnel.c b/net/ipv4/ip_tunnel.c > index 893f013..5dcf50c 100644 > --- a/net/ipv4/ip_tunnel.c > +++ b/net/ipv4/ip_tunnel.c > @@ -515,9 +515,10 @@ static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb, > mtu = dst_mtu(&rt->dst) - dev->hard_header_len > - sizeof(struct iphdr) - tunnel_hlen; > else > - mtu = skb_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu; > + mtu = skb_valid_dst(skb) ? dst_mtu(skb_dst(skb)) : dev->mtu; > > - skb_dst_update_pmtu(skb, mtu); > + if (skb_valid_dst(skb)) > + skb_dst_update_pmtu(skb, mtu); > > if (skb->protocol == htons(ETH_P_IP)) { > if (!skb_is_gso(skb) && > @@ -530,9 +531,11 @@ static int tnl_update_pmtu(struct net_device *dev, struct sk_buff *skb, > } > #if IS_ENABLED(CONFIG_IPV6) > else if (skb->protocol == htons(ETH_P_IPV6)) { > - struct rt6_info *rt6 = (struct rt6_info *)skb_dst(skb); > + struct rt6_info *rt6; > __be32 daddr; > > + rt6 = skb_valid_dst(skb) ? (struct rt6_info *)skb_dst(skb) : > + NULL; > daddr = md ? dst : tunnel->parms.iph.daddr; > > if (rt6 && mtu < dst_mtu(skb_dst(skb)) && > -- > 1.8.3.1 >