Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0xf2/0x150 lib/dump_stack.c:119
 dump_stack+0x15/0x20 lib/dump_stack.c:128
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail_ex+0x229/0x230 lib/fault-inject.c:153
 should_fail+0xb/0x10 lib/fault-inject.c:163
 should_fail_usercopy+0x1a/0x20 lib/fault-inject-usercopy.c:37
 _copy_from_user+0x1e/0xd0 lib/usercopy.c:20
 copy_from_user include/linux/uaccess.h:183 [inline]
 scsi_get_cdrom_generic_arg drivers/scsi/scsi_ioctl.c:744 [inline]
 scsi_cdrom_send_packet drivers/scsi/scsi_ioctl.c:786 [inline]
 scsi_ioctl+0x34e/0x1540 drivers/scsi/scsi_ioctl.c:903
 sg_ioctl+0xd06/0x1870 drivers/scsi/sg.c:1166
==================================================================
BUG: KCSAN: data-race in data_alloc / prb_reserve

write to 0xffffffff86679688 of 8 bytes by task 23664 on cpu 1:
 data_alloc+0x291/0x2c0 kernel/printk/printk_ringbuffer.c:1096
 prb_reserve+0x85e/0xb60 kernel/printk/printk_ringbuffer.c:1669
 vprintk_store+0x53f/0x810 kernel/printk/printk.c:2269
 vprintk_emit+0x10c/0x5e0 kernel/printk/printk.c:2329
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2363
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2373
 set_capacity_and_notify+0xff/0x160 block/genhd.c:86
 loop_set_size+0x2e/0x70 drivers/block/loop.c:232
 loop_configure+0x8b9/0xa40 drivers/block/loop.c:1102
 lo_ioctl+0x5fc/0x11d0
 blkdev_ioctl+0x35f/0x450 block/ioctl.c:676
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xd3/0x150 fs/ioctl.c:893
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:893
 x64_sys_call+0x1688/0x2e00 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

read to 0xffffffff86679688 of 8 bytes by task 23660 on cpu 0:
 desc_read kernel/printk/printk_ringbuffer.c:482 [inline]
 desc_push_tail kernel/printk/printk_ringbuffer.c:778 [inline]
 desc_reserve kernel/printk/printk_ringbuffer.c:924 [inline]
 prb_reserve+0x235/0xb60 kernel/printk/printk_ringbuffer.c:1619
 vprintk_store+0x53f/0x810 kernel/printk/printk.c:2269
 vprintk_emit+0x10c/0x5e0 kernel/printk/printk.c:2329
 vprintk_default+0x26/0x30 kernel/printk/printk.c:2363
 vprintk+0x75/0x80 kernel/printk/printk_safe.c:45
 _printk+0x7a/0xa0 kernel/printk/printk.c:2373
 printk_stack_address arch/x86/kernel/dumpstack.c:72 [inline]
 show_trace_log_lvl+0x430/0x510 arch/x86/kernel/dumpstack.c:285
 __dump_stack lib/dump_stack.c:93 [inline]
 dump_stack_lvl+0xf2/0x150 lib/dump_stack.c:119
 dump_stack+0x15/0x20 lib/dump_stack.c:128
 fail_dump lib/fault-inject.c:52 [inline]
 should_fail_ex+0x229/0x230 lib/fault-inject.c:153
 should_fail+0xb/0x10 lib/fault-inject.c:163
 should_fail_usercopy+0x1a/0x20 lib/fault-inject-usercopy.c:37
 _copy_from_user+0x1e/0xd0 lib/usercopy.c:20
 copy_from_user include/linux/uaccess.h:183 [inline]
 scsi_get_cdrom_generic_arg drivers/scsi/scsi_ioctl.c:744 [inline]
 scsi_cdrom_send_packet drivers/scsi/scsi_ioctl.c:786 [inline]
 scsi_ioctl+0x34e/0x1540 drivers/scsi/scsi_ioctl.c:903
 sg_ioctl+0xd06/0x1870 drivers/scsi/sg.c:1166
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xd3/0x150 fs/ioctl.c:893
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:893
 x64_sys_call+0x1688/0x2e00 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

value changed: 0x00000000000ab690 -> 0x0000000000159c28

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 23660 Comm: syz.2.5617 Not tainted 6.10.0-syzkaller-12710-g3a7e02c040b1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
==================================================================
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:907 [inline]
 __se_sys_ioctl+0xd3/0x150 fs/ioctl.c:893
 __x64_sys_ioctl+0x43/0x50 fs/ioctl.c:893
 x64_sys_call+0x1688/0x2e00 arch/x86/include/generated/asm/syscalls_64.h:17
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xc9/0x1c0 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f116e957299
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:00007f116d5d7048 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007f116eae5f80 RCX: 00007f116e957299
RDX: 0000000020000000 RSI: 0000000000005393 RDI: 0000000000000005
RBP: 00007f116d5d70a0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 000000000000000b R14: 00007f116eae5f80 R15: 00007ffd80bb17d8
 </TASK>