==================================================================
BUG: KASAN: use-after-free in scr_memcpyw include/linux/vt_buffer.h:38 [inline]
BUG: KASAN: use-after-free in fbcon_prepare_logo+0xa03/0xc70 drivers/video/fbdev/core/fbcon.c:613
Read of size 256 at addr ffff88804934fffe by task syz.3.1638/13633

CPU: 1 UID: 0 PID: 13633 Comm: syz.3.1638 Not tainted 6.15.0-rc5-syzkaller-00300-g3ce9925823c7 #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:94 [inline]
 dump_stack_lvl+0x116/0x1f0 lib/dump_stack.c:120
 print_address_description mm/kasan/report.c:408 [inline]
 print_report+0xc3/0x670 mm/kasan/report.c:521
 kasan_report+0xe0/0x110 mm/kasan/report.c:634
 check_region_inline mm/kasan/generic.c:183 [inline]
 kasan_check_range+0xef/0x1a0 mm/kasan/generic.c:189
 __asan_memcpy+0x23/0x60 mm/kasan/shadow.c:105
 scr_memcpyw include/linux/vt_buffer.h:38 [inline]
 fbcon_prepare_logo+0xa03/0xc70 drivers/video/fbdev/core/fbcon.c:613
 fbcon_init+0xd77/0x1900 drivers/video/fbdev/core/fbcon.c:1145
 visual_init+0x31d/0x620 drivers/tty/vt/vt.c:1011
 do_bind_con_driver.isra.0+0x57a/0xbf0 drivers/tty/vt/vt.c:3831
 vt_bind drivers/tty/vt/vt.c:3987 [inline]
 store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4059
 dev_attr_store+0x55/0x80 drivers/base/core.c:2440
 sysfs_kf_write+0xef/0x150 fs/sysfs/file.c:145
 kernfs_fop_write_iter+0x351/0x510 fs/kernfs/file.c:334
 new_sync_write fs/read_write.c:591 [inline]
 vfs_write+0x5ba/0x1180 fs/read_write.c:684
 ksys_write+0x12a/0x240 fs/read_write.c:736
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0x230 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f518db8e969
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:00007f518b9f6038 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f518ddb6160 RCX: 00007f518db8e969
RDX: 00000000fffffdef RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007f518dc10ab1 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f518ddb6160 R15: 00007ffc093f0ec8
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x3431 pfn:0x4934f
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: 0000000000003431 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Movable, gfp_mask 0x140cca(GFP_HIGHUSER_MOVABLE|__GFP_COMP), pid 13282, tgid 13282 (syz.1.1558), ts 502989847629, free_ts 509616035830
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x181/0x1b0 mm/page_alloc.c:1718
 prep_new_page mm/page_alloc.c:1726 [inline]
 get_page_from_freelist+0x135c/0x3920 mm/page_alloc.c:3688
 __alloc_frozen_pages_noprof+0x263/0x23a0 mm/page_alloc.c:4970
 alloc_pages_mpol+0x1fb/0x550 mm/mempolicy.c:2301
 folio_alloc_mpol_noprof+0x36/0x2f0 mm/mempolicy.c:2320
 shmem_alloc_folio+0x135/0x160 mm/shmem.c:1854
 shmem_alloc_and_add_folio+0x499/0xc20 mm/shmem.c:1893
 shmem_get_folio_gfp+0x687/0x1530 mm/shmem.c:2533
 shmem_get_folio mm/shmem.c:2639 [inline]
 shmem_write_begin+0x160/0x300 mm/shmem.c:3289
 generic_perform_write+0x3cd/0x930 mm/filemap.c:4103
 shmem_file_write_iter+0x10e/0x140 mm/shmem.c:3464
 __kernel_write_iter+0x317/0xa90 fs/read_write.c:617
 dump_emit_page fs/coredump.c:885 [inline]
 dump_user_range+0x418/0xb30 fs/coredump.c:959
 elf_core_dump+0x288a/0x3a90 fs/binfmt_elf.c:2128
 do_coredump+0x3183/0x4480 fs/coredump.c:759
 get_signal+0x22e3/0x26d0 kernel/signal.c:3019
page last free pid 13282 tgid 13282 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1262 [inline]
 free_unref_folios+0x999/0x1630 mm/page_alloc.c:2782
 folios_put_refs+0x56f/0x740 mm/swap.c:992
 folio_batch_release include/linux/pagevec.h:101 [inline]
 shmem_undo_range+0x58f/0x1150 mm/shmem.c:1125
 shmem_truncate_range mm/shmem.c:1237 [inline]
 shmem_evict_inode+0x3a1/0xbe0 mm/shmem.c:1365
 evict+0x3e3/0x920 fs/inode.c:810
 iput_final fs/inode.c:1898 [inline]
 iput fs/inode.c:1924 [inline]
 iput+0x521/0x880 fs/inode.c:1910
 dentry_unlink_inode+0x29c/0x480 fs/dcache.c:457
 __dentry_kill+0x1d0/0x600 fs/dcache.c:660
 dput.part.0+0x4b1/0x9b0 fs/dcache.c:902
 dput+0x1f/0x30 fs/dcache.c:892
 __fput+0x51c/0xb70 fs/file_table.c:473
 task_work_run+0x14d/0x240 kernel/task_work.c:227
 exit_task_work include/linux/task_work.h:40 [inline]
 do_exit+0xafb/0x2c30 kernel/exit.c:953
 do_group_exit+0xd3/0x2a0 kernel/exit.c:1102
 get_signal+0x2673/0x26d0 kernel/signal.c:3034
 arch_do_signal_or_restart+0x8f/0x7a0 arch/x86/kernel/signal.c:337

Memory state around the buggy address:
 ffff88804934fe80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88804934ff00: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff88804934ff80: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                                                ^
 ffff888049350000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888049350080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
==================================================================