Hello, syzbot found the following issue on: HEAD commit: 05d3ef8bba77 Linux 6.6-rc7 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=120b3971680000 kernel config: https://syzkaller.appspot.com/x/.config?x=667b53b8e7487997 dashboard link: https://syzkaller.appspot.com/bug?extid=c71bc336c5061153b502 compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/a9faa0dd3d80/disk-05d3ef8b.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/cea22e55cef7/vmlinux-05d3ef8b.xz kernel image: https://storage.googleapis.com/syzbot-assets/d0679f322d2a/bzImage-05d3ef8b.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+c71bc336c5061153b502@xxxxxxxxxxxxxxxxxxxxxxxxx general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 1 PID: 1906 Comm: syz-executor.4 Not tainted 6.6.0-rc7-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023 RIP: 0010:ccid_hc_tx_send_packet net/dccp/ccid.h:166 [inline] RIP: 0010:dccp_write_xmit+0x66/0x1d0 net/dccp/output.c:356 Code: 00 48 85 c0 49 89 c4 0f 84 03 01 00 00 e8 52 d8 0c f8 41 80 3e 00 0f 85 45 01 00 00 48 8b 9d f8 08 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 0f 85 1f 01 00 00 48 8b 1b 48 8d bb b0 00 00 00 48 RSP: 0018:ffffc90004cff870 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff888016f85940 RSI: ffffffff897af1de RDI: ffff888020ba5c40 RBP: ffff888020ba5c40 R08: 0000000000000001 R09: fffffbfff2339be7 R10: ffffffff919cdf3f R11: 0000000000000000 R12: ffff888075c38280 R13: dffffc0000000000 R14: ffffed1004174ca7 R15: ffff888020ba6538 FS: 00007f31f81d66c0(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f9c878ffc83 CR3: 0000000066952000 CR4: 00000000003506e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: <TASK> dccp_sendmsg+0x968/0xcc0 net/dccp/proto.c:801 inet_sendmsg+0x9d/0xe0 net/ipv4/af_inet.c:846 sock_sendmsg_nosec net/socket.c:730 [inline] __sock_sendmsg+0xd5/0x180 net/socket.c:745 ____sys_sendmsg+0x2ac/0x940 net/socket.c:2558 ___sys_sendmsg+0x135/0x1d0 net/socket.c:2612 __sys_sendmmsg+0x1a1/0x450 net/socket.c:2698 __do_sys_sendmmsg net/socket.c:2727 [inline] __se_sys_sendmmsg net/socket.c:2724 [inline] __x64_sys_sendmmsg+0x9c/0x100 net/socket.c:2724 do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x63/0xcd RIP: 0033:0x7f31f747cae9 Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 e1 20 00 00 90 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 b0 ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f31f81d60c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000133 RAX: ffffffffffffffda RBX: 00007f31f759c050 RCX: 00007f31f747cae9 RDX: 0000000000000002 RSI: 00000000200014c0 RDI: 0000000000000004 RBP: 00007f31f74c847a R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 000000000000000b R14: 00007f31f759c050 R15: 00007f31f76bfa48 </TASK> Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:ccid_hc_tx_send_packet net/dccp/ccid.h:166 [inline] RIP: 0010:dccp_write_xmit+0x66/0x1d0 net/dccp/output.c:356 Code: 00 48 85 c0 49 89 c4 0f 84 03 01 00 00 e8 52 d8 0c f8 41 80 3e 00 0f 85 45 01 00 00 48 8b 9d f8 08 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 28 00 0f 85 1f 01 00 00 48 8b 1b 48 8d bb b0 00 00 00 48 RSP: 0018:ffffc90004cff870 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: ffff888016f85940 RSI: ffffffff897af1de RDI: ffff888020ba5c40 RBP: ffff888020ba5c40 R08: 0000000000000001 R09: fffffbfff2339be7 R10: ffffffff919cdf3f R11: 0000000000000000 R12: ffff888075c38280 R13: dffffc0000000000 R14: ffffed1004174ca7 R15: ffff888020ba6538 FS: 00007f31f81d66c0(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f5f4e398000 CR3: 0000000066952000 CR4: 00000000003506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess): 0: 00 48 85 add %cl,-0x7b(%rax) 3: c0 49 89 c4 rorb $0xc4,-0x77(%rcx) 7: 0f 84 03 01 00 00 je 0x110 d: e8 52 d8 0c f8 call 0xf80cd864 12: 41 80 3e 00 cmpb $0x0,(%r14) 16: 0f 85 45 01 00 00 jne 0x161 1c: 48 8b 9d f8 08 00 00 mov 0x8f8(%rbp),%rbx 23: 48 89 d8 mov %rbx,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 42 80 3c 28 00 cmpb $0x0,(%rax,%r13,1) <-- trapping instruction 2f: 0f 85 1f 01 00 00 jne 0x154 35: 48 8b 1b mov (%rbx),%rbx 38: 48 8d bb b0 00 00 00 lea 0xb0(%rbx),%rdi 3f: 48 rex.W --- 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@xxxxxxxxxxxxxxxx. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the bug is already fixed, let syzbot know by replying with: #syz fix: exact-commit-title If you want to overwrite bug's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the bug is a duplicate of another bug, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup
