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References: <000000000000e1609a061d5330ce@google.com> <5e4905d7-32e1-4359-9720-a32330aec424@redhat.com> <87wmll7i9n.fsf@cloudflare.com> In-Reply-To: <87wmll7i9n.fsf@cloudflare.com> From: Eric Dumazet Date: Tue, 16 Jul 2024 07:54:00 -0700 Message-ID: Subject: Re: [syzbot] [net?] WARNING in skb_warn_bad_offload (5) To: Jakub Sitnicki Cc: Paolo Abeni , syzbot , davem@davemloft.net, dsahern@kernel.org, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, soheil@google.com, syzkaller-bugs@googlegroups.com, willemb@google.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, Jul 16, 2024 at 3:17=E2=80=AFAM Jakub Sitnicki wrote: > > On Tue, Jul 16, 2024 at 12:04 PM +02, Paolo Abeni wrote: > > On 7/16/24 03:23, syzbot wrote: > >> syzbot found the following issue on: > >> HEAD commit: 80ab5445da62 Merge tag 'wireless-next-2024-07-11' of g= it:/.. > >> git tree: net-next > >> console+strace: https://syzkaller.appspot.com/x/log.txt?x=3D175fb82198= 0000 > >> kernel config: https://syzkaller.appspot.com/x/.config?x=3D2dbcdd8641= c4638f > >> dashboard link: https://syzkaller.appspot.com/bug?extid=3De15b7e15b8a7= 51a91d9a > >> compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for = Debian) 2.40 > >> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=3D172bf566= 980000 > >> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=3D12fff53598= 0000 > >> Downloadable assets: > >> disk image: https://storage.googleapis.com/syzbot-assets/184da3869c30/= disk-80ab5445.raw.xz > >> vmlinux: https://storage.googleapis.com/syzbot-assets/85bfe9b60f21/vml= inux-80ab5445.xz > >> kernel image: https://storage.googleapis.com/syzbot-assets/06064623a94= 8/bzImage-80ab5445.xz > >> The issue was bisected to: > >> commit 10154dbded6d6a2fecaebdfda206609de0f121a9 > >> Author: Jakub Sitnicki > >> Date: Wed Jun 26 17:51:26 2024 +0000 > >> udp: Allow GSO transmit from devices with no checksum offload > >> bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=3D142ccbe= d980000 > >> final oops: https://syzkaller.appspot.com/x/report.txt?x=3D162ccbe= d980000 > >> console output: https://syzkaller.appspot.com/x/log.txt?x=3D122ccbed98= 0000 > >> IMPORTANT: if you fix the issue, please add the following tag to the c= ommit: > >> Reported-by: syzbot+e15b7e15b8a751a91d9a@syzkaller.appspotmail.com > >> Fixes: 10154dbded6d ("udp: Allow GSO transmit from devices with no che= cksum offload") > >> skb frag: 00000080: 62 3f 77 e4 0e 82 0d 2f 85 cc 44 ea 25 5a 99 7= 6 > >> skb frag: 00000090: f2 53 > >> ------------[ cut here ]------------ > >> ip6tnl0: caps=3D(0x00000006401d7869, 0x00000006401d7869) > >> WARNING: CPU: 0 PID: 5112 at net/core/dev.c:3293 skb_warn_bad_offload+= 0x166/0x1a0 net/core/dev.c:3291 > >> Modules linked in: > >> CPU: 0 PID: 5112 Comm: syz-executor391 Not tainted 6.10.0-rc7-syzkalle= r-01603-g80ab5445da62 #0 > >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIO= S Google 06/07/2024 > >> RIP: 0010:skb_warn_bad_offload+0x166/0x1a0 net/core/dev.c:3291 > >> Code: e8 5f 94 a3 f8 49 8b 04 24 48 8d 88 a0 03 00 00 48 85 c0 48 0f 4= 4 cd 48 c7 c7 00 cc c5 8c 4c 89 f6 48 89 da e8 fb 92 ff f7 90 <0f> 0b 90 90= 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc 44 89 f9 > >> RSP: 0018:ffffc900034bedc8 EFLAGS: 00010246 > >> RAX: 7d287cad4185da00 RBX: ffff888040cdc0b8 RCX: ffff888023d1bc00 > >> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 > >> RBP: ffffffff8cc5cbc0 R08: ffffffff815857b2 R09: fffffbfff1c39994 > >> R10: dffffc0000000000 R11: fffffbfff1c39994 R12: ffff888022880518 > >> R13: dffffc0000000000 R14: ffff888040cdc130 R15: ffff888040cdc130 > >> FS: 000055556e9e9380(0000) GS:ffff8880b9400000(0000) knlGS:0000000000= 000000 > >> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > >> CR2: 0000000020001180 CR3: 000000007c876000 CR4: 00000000003506f0 > >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > >> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > >> Call Trace: > >> > >> __skb_gso_segment+0x3be/0x4c0 net/core/gso.c:127 > >> skb_gso_segment include/net/gso.h:83 [inline] > >> validate_xmit_skb+0x585/0x1120 net/core/dev.c:3661 > >> __dev_queue_xmit+0x17a4/0x3e90 net/core/dev.c:4415 > >> neigh_output include/net/neighbour.h:542 [inline] > >> ip6_finish_output2+0xffa/0x1680 net/ipv6/ip6_output.c:137 > >> ip6_finish_output+0x41e/0x810 net/ipv6/ip6_output.c:222 > >> ip6_send_skb+0x112/0x230 net/ipv6/ip6_output.c:1958 > >> udp_v6_send_skb+0xbf5/0x1870 net/ipv6/udp.c:1292 > >> udpv6_sendmsg+0x23b3/0x3270 net/ipv6/udp.c:1588 > >> sock_sendmsg_nosec net/socket.c:730 [inline] > >> __sock_sendmsg+0xef/0x270 net/socket.c:745 > >> ____sys_sendmsg+0x525/0x7d0 net/socket.c:2585 > >> ___sys_sendmsg net/socket.c:2639 [inline] > >> __sys_sendmmsg+0x3b2/0x740 net/socket.c:2725 > >> __do_sys_sendmmsg net/socket.c:2754 [inline] > >> __se_sys_sendmmsg net/socket.c:2751 [inline] > >> __x64_sys_sendmmsg+0xa0/0xb0 net/socket.c:2751 > >> do_syscall_x64 arch/x86/entry/common.c:52 [inline] > >> do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 > >> entry_SYSCALL_64_after_hwframe+0x77/0x7f > >> RIP: 0033:0x7f04f688fe89 > >> Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 01 1a 00 00 90 48 89 f8 48 8= 9 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 b8 ff ff ff f7 d8 64 89 01 48 > >> RSP: 002b:00007ffeebc526e8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 > >> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007f04f688fe89 > >> RDX: 0000000000000001 RSI: 0000000020003cc0 RDI: 0000000000000003 > >> RBP: 00000000000f4240 R08: 0000000000000000 R09: 0000000000000001 > >> R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffeebc52740 > >> R13: 00007f04f68dd406 R14: 0000000000000003 R15: 00007ffeebc52720 > >> > > > > Looking at the console log, the the relevant GSO packet is an UFO one w= ith > > CSUM_NONE. commit 10154dbded6d6a2fecaebdfda206609de0f121a9 only adjust = the skb > > csum for USO packets. @Jakub S. could you please have a look? > > Will do. Thanks for the hint. The trigger for the bug is the following : setsockopt(3, SOL_IPV6, IPV6_HOPOPTS, "\0\3\0\0\0\0\0\0\5\2\0\0\0\1\0\302\4\200\0\0\0\5\2\0\6\302\4\0\0\0\1\302".= .., 40) =3D 0 Some random IPV6_HOPTS, with multiple IPV6_TLV_JUMBO options Non GSO path sends a malformed packet just fine, but GSO complains loudly. (flowlabel 0x754ca, hlim 64, next-header Options (0) payload length: 186) localhost > localhost: HBH (pad1)(pad1)(pad1)(pad1)(pad1)(pad1)(rtalert: 0x0000) (pad1)(padn)(jumbo: 2147483648 - payload len !=3D 0) (rtalert: 0x0006) (jumbo: 1 - already seen) [|hbhopt]