Hello, syzbot found the following issue on: HEAD commit: a3fa7a101dcf Merge branches 'akpm' and 'akpm-hotfixes' (pa.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17da7b93300000 kernel config: https://syzkaller.appspot.com/x/.config?x=ddf81d5d49fe3452 dashboard link: https://syzkaller.appspot.com/bug?extid=337de45f13a4fd54d708 compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=129e9da5300000 The issue was bisected to: commit fa84693b3c896460831fe0750554121121a23da8 Author: Jens Axboe <axboe@xxxxxxxxx> Date: Wed Sep 1 20:15:59 2021 +0000 io_uring: ensure IORING_REGISTER_IOWQ_MAX_WORKERS works with SQPOLL bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=164900c3300000 final oops: https://syzkaller.appspot.com/x/report.txt?x=154900c3300000 console output: https://syzkaller.appspot.com/x/log.txt?x=114900c3300000 IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+337de45f13a4fd54d708@xxxxxxxxxxxxxxxxxxxxxxxxx Fixes: fa84693b3c89 ("io_uring: ensure IORING_REGISTER_IOWQ_MAX_WORKERS works with SQPOLL") general protection fault, probably for non-canonical address 0xdffffc0000000103: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000818-0x000000000000081f] CPU: 0 PID: 12816 Comm: syz-executor.1 Not tainted 5.14.0-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:io_register_iowq_max_workers fs/io_uring.c:10552 [inline] RIP: 0010:__io_uring_register fs/io_uring.c:10757 [inline] RIP: 0010:__do_sys_io_uring_register+0x10e9/0x2e70 fs/io_uring.c:10792 Code: ea 03 80 3c 02 00 0f 85 43 1b 00 00 48 8b 9b a8 00 00 00 b8 ff ff 37 00 48 c1 e0 2a 48 8d bb 18 08 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 11 1b 00 00 48 8b 9b 18 08 00 00 48 85 db 0f 84 RSP: 0018:ffffc90003f3fdf8 EFLAGS: 00010206 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000103 RSI: 0000000000000004 RDI: 0000000000000818 RBP: ffff888073777900 R08: 0000000000000000 R09: ffff88807e916413 R10: ffffed100fd22c82 R11: 0000000000000001 R12: 0000000000000000 R13: ffffc90003f3fec8 R14: 1ffff920007e7fc9 R15: ffff88805cd7e000 FS: 00007f6c631e3700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001907808 CR3: 0000000062c6d000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: do_syscall_x64 arch/x86/entry/common.c:50 [inline] do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80 entry_SYSCALL_64_after_hwframe+0x44/0xae RIP: 0033:0x4665f9 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 bc ff ff ff f7 d8 64 89 01 48 RSP: 002b:00007f6c631e3188 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab RAX: ffffffffffffffda RBX: 000000000056c038 RCX: 00000000004665f9 RDX: 0000000020004000 RSI: 0000000000000013 RDI: 0000000000000003 RBP: 00000000004bfcc4 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000002 R11: 0000000000000246 R12: 000000000056c038 R13: 00007ffdd807e0af R14: 00007f6c631e3300 R15: 0000000000022000 Modules linked in: ---[ end trace 1cd60a7726ee853d ]--- RIP: 0010:io_register_iowq_max_workers fs/io_uring.c:10552 [inline] RIP: 0010:__io_uring_register fs/io_uring.c:10757 [inline] RIP: 0010:__do_sys_io_uring_register+0x10e9/0x2e70 fs/io_uring.c:10792 Code: ea 03 80 3c 02 00 0f 85 43 1b 00 00 48 8b 9b a8 00 00 00 b8 ff ff 37 00 48 c1 e0 2a 48 8d bb 18 08 00 00 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 11 1b 00 00 48 8b 9b 18 08 00 00 48 85 db 0f 84 RSP: 0018:ffffc90003f3fdf8 EFLAGS: 00010206 RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000103 RSI: 0000000000000004 RDI: 0000000000000818 RBP: ffff888073777900 R08: 0000000000000000 R09: ffff88807e916413 R10: ffffed100fd22c82 R11: 0000000000000001 R12: 0000000000000000 R13: ffffc90003f3fec8 R14: 1ffff920007e7fc9 R15: ffff88805cd7e000 FS: 00007f6c631e3700(0000) GS:ffff8880b9c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007fb988f6b000 CR3: 0000000062c6d000 CR4: 00000000001506f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 ---------------- Code disassembly (best guess), 1 bytes skipped: 0: 03 80 3c 02 00 0f add 0xf00023c(%rax),%eax 6: 85 43 1b test %eax,0x1b(%rbx) 9: 00 00 add %al,(%rax) b: 48 8b 9b a8 00 00 00 mov 0xa8(%rbx),%rbx 12: b8 ff ff 37 00 mov $0x37ffff,%eax 17: 48 c1 e0 2a shl $0x2a,%rax 1b: 48 8d bb 18 08 00 00 lea 0x818(%rbx),%rdi 22: 48 89 fa mov %rdi,%rdx 25: 48 c1 ea 03 shr $0x3,%rdx * 29: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction 2d: 0f 85 11 1b 00 00 jne 0x1b44 33: 48 8b 9b 18 08 00 00 mov 0x818(%rbx),%rbx 3a: 48 85 db test %rbx,%rbx 3d: 0f .byte 0xf 3e: 84 .byte 0x84 --- 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. For information about bisection process see: https://goo.gl/tpsmEJ#bisection syzbot can test patches for this issue, for details see: https://goo.gl/tpsmEJ#testing-patches
