lo_rw_aio(loop3) starting read with raw_refcnt=0x0, refcnt=1 lo_rw_aio(loop3) starting write with NULL file (already cleared?) Oops: general protection fault, probably for non-canonical address 0xdffffc0000000014: 0000 [#1] SMP KASAN PTI KASAN: null-ptr-deref in range [0x00000000000000a0-0x00000000000000a7] CPU: 1 UID: 0 PID: 89 Comm: kworker/u8:5 Tainted: G L syzkaller #0 PREEMPT_{RT,(full)} Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Workqueue: loop3 loop_workfn RIP: 0010:file_inode include/linux/fs.h:1353 [inline] RIP: 0010:kiocb_start_write include/linux/fs.h:2756 [inline] RIP: 0010:lo_rw_aio+0xd1d/0x1170 drivers/block/loop.c:412 Code: 34 fc 45 85 f6 0f 84 d2 00 00 00 43 80 7c 25 00 00 74 08 4c 89 ff e8 62 af 9d fc bb a0 00 00 00 49 03 1f 48 89 d8 48 c1 e8 03 <42> 80 3c 20 00 74 08 48 89 df e8 44 af 9d fc 48 8b 1b 48 83 c3 28 RSP: 0018:ffffc9000154f680 EFLAGS: 00010206 RAX: 0000000000000014 RBX: 00000000000000a0 RCX: ffff88801abf9ec0 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000154f7f0 R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: fffff520002a9e81 R12: dffffc0000000000 R13: 1ffff11004d1f496 R14: 0000000000000001 R15: ffff8880268fa4b0 FS: 0000000000000000(0000) GS:ffff88812601f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f195a595fc0 CR3: 000000003395c000 CR4: 00000000003526f0 Call Trace: do_req_filebacked drivers/block/loop.c:444 [inline] loop_handle_cmd drivers/block/loop.c:1940 [inline] loop_process_work+0x637/0x11b0 drivers/block/loop.c:1975 process_one_work+0x98b/0x1630 kernel/workqueue.c:3306 process_scheduled_works kernel/workqueue.c:3389 [inline] worker_thread+0xb49/0x1140 kernel/workqueue.c:3470 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 Modules linked in: ---[ end trace 0000000000000000 ]--- RIP: 0010:file_inode include/linux/fs.h:1353 [inline] RIP: 0010:kiocb_start_write include/linux/fs.h:2756 [inline] RIP: 0010:lo_rw_aio+0xd1d/0x1170 drivers/block/loop.c:412 Code: 34 fc 45 85 f6 0f 84 d2 00 00 00 43 80 7c 25 00 00 74 08 4c 89 ff e8 62 af 9d fc bb a0 00 00 00 49 03 1f 48 89 d8 48 c1 e8 03 <42> 80 3c 20 00 74 08 48 89 df e8 44 af 9d fc 48 8b 1b 48 83 c3 28 RSP: 0018:ffffc9000154f680 EFLAGS: 00010206 RAX: 0000000000000014 RBX: 00000000000000a0 RCX: ffff88801abf9ec0 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc9000154f7f0 R08: 0000000000000000 R09: 0000000000000000 R10: dffffc0000000000 R11: fffff520002a9e81 R12: dffffc0000000000 R13: 1ffff11004d1f496 R14: 0000000000000001 R15: ffff8880268fa4b0 FS: 0000000000000000(0000) GS:ffff88812601f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f195a595fc0 CR3: 000000003395c000 CR4: 00000000003526f0 ---------------- Code disassembly (best guess): 0: 34 fc xor $0xfc,%al 2: 45 85 f6 test %r14d,%r14d 5: 0f 84 d2 00 00 00 je 0xdd b: 43 80 7c 25 00 00 cmpb $0x0,0x0(%r13,%r12,1) 11: 74 08 je 0x1b 13: 4c 89 ff mov %r15,%rdi 16: e8 62 af 9d fc call 0xfc9daf7d 1b: bb a0 00 00 00 mov $0xa0,%ebx 20: 49 03 1f add (%r15),%rbx 23: 48 89 d8 mov %rbx,%rax 26: 48 c1 e8 03 shr $0x3,%rax * 2a: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) <-- trapping instruction 2f: 74 08 je 0x39 31: 48 89 df mov %rbx,%rdi 34: e8 44 af 9d fc call 0xfc9daf7d 39: 48 8b 1b mov (%rbx),%rbx 3c: 48 83 c3 28 add $0x28,%rbx