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BUG: KASAN: null-ptr-deref in io_sqe_buffer_register+0x369/0x20a0
Read of size 8 at addr 0000000000000000 by task syz.2.625/7694

CPU: 1 UID: 0 PID: 7694 Comm: syz.2.625 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0x189/0x250
 kasan_report+0x118/0x150
 kasan_check_range+0x2b0/0x2c0
 io_sqe_buffer_register+0x369/0x20a0
 __io_register_rsrc_update+0x55e/0x11b0
 io_register_rsrc_update+0x196/0x1a0
 __se_sys_io_uring_register+0x795/0x11b0
 do_syscall_64+0xfa/0xfa0
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fe50fb8ebe9
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:00007fe50ddd5038 EFLAGS: 00000246 ORIG_RAX: 00000000000001ab
RAX: ffffffffffffffda RBX: 00007fe50fdc6180 RCX: 00007fe50fb8ebe9
RDX: 00002000000003c0 RSI: 0000000000000010 RDI: 0000000000000005
RBP: 00007fe50fc11e19 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000020 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe50fdc6218 R14: 00007fe50fdc6180 R15: 00007ffcb76d6298
 </TASK>
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