loop8: detected capacity change from 0 to 512
EXT4-fs (loop8): Encoding requested by superblock is unknown
Console: switching to colour VGA+ 80x25
==================================================================
BUG: KASAN: slab-out-of-bounds in scr_memcpyw include/linux/vt_buffer.h:49 [inline]
BUG: KASAN: slab-out-of-bounds in fbcon_prepare_logo+0x4e2/0xa70 drivers/video/fbdev/core/fbcon.c:602
Read of size 100 at addr ffff888021ddffc4 by task syz.8.11920/12311

CPU: 0 PID: 12311 Comm: syz.8.11920 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
Call Trace:
 <TASK>
 dump_stack_lvl+0x18c/0x250 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:364 [inline]
 print_report+0xa8/0x210 mm/kasan/report.c:468
 kasan_report+0x117/0x150 mm/kasan/report.c:581
 check_region_inline mm/kasan/generic.c:-1 [inline]
 kasan_check_range+0x241/0x290 mm/kasan/generic.c:187
 __asan_memcpy+0x29/0x70 mm/kasan/shadow.c:105
 scr_memcpyw include/linux/vt_buffer.h:49 [inline]
 fbcon_prepare_logo+0x4e2/0xa70 drivers/video/fbdev/core/fbcon.c:602
 fbcon_init+0x1380/0x2460 drivers/video/fbdev/core/fbcon.c:1137
 visual_init+0x2dd/0x650 drivers/tty/vt/vt.c:1023
 do_bind_con_driver+0x859/0x1030 drivers/tty/vt/vt.c:3645
 vt_bind drivers/tty/vt/vt.c:3801 [inline]
 store_bind+0x798/0xa20 drivers/tty/vt/vt.c:3873
 kernfs_fop_write_iter+0x3a4/0x520 fs/kernfs/file.c:352
 call_write_iter include/linux/fs.h:2018 [inline]
 new_sync_write fs/read_write.c:491 [inline]
 vfs_write+0x474/0x9a0 fs/read_write.c:584
 ksys_write+0x151/0x260 fs/read_write.c:637
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x55/0xb0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7fe19299e159
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 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 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fe19387e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fe192c25fa0 RCX: 00007fe19299e159
RDX: 0000000000000001 RSI: 0000200000000280 RDI: 0000000000000004
RBP: 00007fe192a35024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fe192c26038 R14: 00007fe192c25fa0 R15: 00007ffe68eaf9f8
 </TASK>

Allocated by task 1:
 kasan_save_stack mm/kasan/common.c:46 [inline]
 kasan_set_track+0x4e/0x70 mm/kasan/common.c:53
 ____kasan_kmalloc mm/kasan/common.c:375 [inline]
 __kasan_kmalloc+0x8f/0xa0 mm/kasan/common.c:384
 kmalloc include/linux/slab.h:600 [inline]
 kzalloc include/linux/slab.h:721 [inline]
 device_create_groups_vargs drivers/base/core.c:4409 [inline]
 device_create+0x13e/0x300 drivers/base/core.c:4466
 bdi_register_va+0x97/0x6d0 mm/backing-dev.c:1011
 bdi_register+0xe3/0x140 mm/backing-dev.c:1043
 device_add_disk+0x78e/0xfe0 block/genhd.c:493
 add_disk include/linux/blkdev.h:748 [inline]
 loop_add+0x6d1/0x990 drivers/block/loop.c:2097
 loop_init+0x177/0x220 drivers/block/loop.c:2289
 do_one_initcall+0x242/0x790 init/main.c:1210
 do_initcall_level+0x13d/0x1f0 init/main.c:1272
 do_initcalls+0x69/0xd0 init/main.c:1288
 kernel_init_freeable+0x3d9/0x560 init/main.c:1525
 kernel_init+0x1d/0x1c0 init/main.c:1415
 ret_from_fork+0x48/0x80 arch/x86/kernel/process.c:152
 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:293

The buggy address belongs to the object at ffff888021ddf000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 2828 bytes to the right of
 allocated 1208-byte region [ffff888021ddf000, ffff888021ddf4b8)

The buggy address belongs to the physical page:
page:ffffea0000877600 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x21dd8
head:ffffea0000877600 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888017c42000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000080008 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x52800(GFP_NOWAIT|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP), pid 1, tgid 1 (swapper/0), ts 6311982196, free_ts 0
 set_page_owner include/linux/page_owner.h:31 [inline]
 post_alloc_hook+0x1c1/0x200 mm/page_alloc.c:1582
 prep_new_page mm/page_alloc.c:1589 [inline]
 get_page_from_freelist+0x2181/0x22a0 mm/page_alloc.c:3221
 __alloc_pages+0x1f0/0x460 mm/page_alloc.c:4501
 alloc_page_interleave+0x24/0x1e0 mm/mempolicy.c:2118
 alloc_slab_page+0x5d/0x180 mm/slub.c:1881
 allocate_slab mm/slub.c:2028 [inline]
 new_slab+0x87/0x2d0 mm/slub.c:2081
 ___slab_alloc+0xc5c/0x12f0 mm/slub.c:3253
 __slab_alloc mm/slub.c:3339 [inline]
 __slab_alloc_node mm/slub.c:3392 [inline]
 slab_alloc_node mm/slub.c:3485 [inline]
 __kmem_cache_alloc_node+0x11f/0x250 mm/slub.c:3534
 kmalloc_node_trace+0x26/0xe0 mm/slab_common.c:1111
 kmalloc_node include/linux/slab.h:616 [inline]
 kzalloc_node include/linux/slab.h:732 [inline]
 throtl_pd_alloc+0x9d/0x5f0 block/blk-throttle.c:344
 blkcg_activate_policy+0x267/0x9e0 block/blk-cgroup.c:1595
 blk_throtl_init+0x39a/0x490 block/blk-throttle.c:2403
 blkcg_init_disk+0x2e8/0x370 block/blk-cgroup.c:1500
 __alloc_disk_node+0x2b7/0x570 block/genhd.c:1375
 __blk_mq_alloc_disk+0xed/0x190 block/blk-mq.c:4322
 loop_add+0x322/0x990 drivers/block/loop.c:2052
page_owner free stack trace missing

Memory state around the buggy address:
 ffff888021ddfe80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888021ddff00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888021ddff80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                           ^
 ffff888021de0000: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888021de0080: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================