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Sun, 27 Jul 2025 21:53:37 +0200 (CEST) From: Charalampos Mitrodimas To: syzbot Cc: davem@davemloft.net, dsahern@kernel.org, edumazet@google.com, herbert@gondor.apana.org.au, horms@kernel.org, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, steffen.klassert@secunet.com, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [net?] WARNING in ah6_output In-Reply-To: <683265d3.a70a0220.253bc2.0079.GAE@google.com> References: <683265d3.a70a0220.253bc2.0079.GAE@google.com> Date: Sun, 27 Jul 2025 19:53:40 +0000 Message-ID: <878qk9csvy.fsf@posteo.net> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain syzbot writes: > Hello, > > syzbot found the following issue on: > > HEAD commit: 9e89db3d847f Merge tag 'linux-can-fixes-for-6.15-20250520'.. > git tree: net > console output: https://syzkaller.appspot.com/x/log.txt?x=1476d1f4580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=c3f0e807ec5d1268 > dashboard link: https://syzkaller.appspot.com/bug?extid=01b0667934cdceb4451c > compiler: Debian clang version 20.1.2 (++20250402124445+58df0ef89dd6-1~exp1~20250402004600.97), Debian LLD 20.1.2 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/8b09322b598e/disk-9e89db3d.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/23ed08e707b5/vmlinux-9e89db3d.xz > kernel image: https://storage.googleapis.com/syzbot-assets/be78b62450e7/bzImage-9e89db3d.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+01b0667934cdceb4451c@syzkaller.appspotmail.com > > ------------[ cut here ]------------ > memcpy: detected field-spanning write (size 40) of single field "&top_iph->saddr" at net/ipv6/ah6.c:439 (size 16) > WARNING: CPU: 0 PID: 8838 at net/ipv6/ah6.c:439 ah6_output+0xe7e/0x14e0 net/ipv6/ah6.c:439 > Modules linked in: > CPU: 0 UID: 0 PID: 8838 Comm: syz.1.814 Not tainted 6.15.0-rc6-syzkaller-00173-g9e89db3d847f #0 PREEMPT(full) > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025 > RIP: 0010:ah6_output+0xe7e/0x14e0 net/ipv6/ah6.c:439 > Code: ff e8 36 80 9f f7 c6 05 bb 97 48 05 01 90 b9 10 00 00 00 48 c7 c7 a0 56 7e 8c 4c 89 fe 48 c7 c2 00 59 7e 8c e8 a3 dc 63 f7 90 <0f> 0b 90 90 e9 b5 fe ff ff e8 74 e4 35 01 48 8b 4c 24 10 80 e1 07 > RSP: 0018:ffffc900049f70e0 EFLAGS: 00010246 > RAX: 3fffcb5d3bcc7c00 RBX: 0000000000000028 RCX: 0000000000080000 > RDX: ffffc9000ece1000 RSI: 00000000000052e8 RDI: 00000000000052e9 > RBP: ffffc900049f7250 R08: 0000000000000003 R09: 0000000000000004 > R10: dffffc0000000000 R11: fffffbfff1bba944 R12: dffffc0000000000 > R13: 1ffff9200093ee38 R14: ffff8881452e8800 R15: 0000000000000028 > FS: 00007fc3a1d2c6c0(0000) GS:ffff8881260c7000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000555569628808 CR3: 000000005cf4e000 CR4: 00000000003526f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > > xfrm_output_one net/xfrm/xfrm_output.c:555 [inline] > xfrm_output_resume+0x2c55/0x6170 net/xfrm/xfrm_output.c:590 > __xfrm6_output+0x2eb/0x1070 net/ipv6/xfrm6_output.c:103 > NF_HOOK_COND include/linux/netfilter.h:303 [inline] > xfrm6_output+0x1c6/0x4f0 net/ipv6/xfrm6_output.c:108 > ip6_send_skb+0x1d5/0x390 net/ipv6/ip6_output.c:1981 > l2tp_ip6_sendmsg+0x1378/0x1870 net/l2tp/l2tp_ip6.c:661 > sock_sendmsg_nosec net/socket.c:712 [inline] > __sock_sendmsg+0x19c/0x270 net/socket.c:727 > ____sys_sendmsg+0x505/0x830 net/socket.c:2566 > ___sys_sendmsg+0x21f/0x2a0 net/socket.c:2620 > __sys_sendmsg net/socket.c:2652 [inline] > __do_sys_sendmsg net/socket.c:2657 [inline] > __se_sys_sendmsg net/socket.c:2655 [inline] > __x64_sys_sendmsg+0x19b/0x260 net/socket.c:2655 > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] > do_syscall_64+0xf6/0x210 arch/x86/entry/syscall_64.c:94 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7fc3a0f8e969 > 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:00007fc3a1d2c038 EFLAGS: 00000246 ORIG_RAX: 000000000000002e > RAX: ffffffffffffffda RBX: 00007fc3a11b6080 RCX: 00007fc3a0f8e969 > RDX: 0000000000000800 RSI: 0000200000000540 RDI: 0000000000000004 > RBP: 00007fc3a1010ab1 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 0000000000000000 R14: 00007fc3a11b6080 R15: 00007ffc18a80a58 > > > > --- > This report is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > If the report is already addressed, let syzbot know by replying with: > #syz fix: exact-commit-title > > If you want to overwrite report's subsystems, reply with: > #syz set subsystems: new-subsystem > (See the list of subsystem names on the web dashboard) > > If the report is a duplicate of another one, reply with: > #syz dup: exact-subject-of-another-report > > If you want to undo deduplication, reply with: > #syz undup #syz test: https://github.com/charmitro/linux.git d4017cef5514575221234e65a2ff9b0713718274