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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:646
Read of size 256 at addr ffff888043c563c0 by task syz.5.3548/22481

CPU: 0 UID: 0 PID: 22481 Comm: syz.5.3548 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
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:378 [inline]
 print_report+0xcd/0x630 mm/kasan/report.c:482
 kasan_report+0xe0/0x110 mm/kasan/report.c:595
 check_region_inline mm/kasan/generic.c:194 [inline]
 kasan_check_range+0x100/0x1b0 mm/kasan/generic.c:200
 __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:646
 fbcon_init+0xda0/0x1930 drivers/video/fbdev/core/fbcon.c:1179
 visual_init+0x320/0x620 drivers/tty/vt/vt.c:1020
 do_bind_con_driver.isra.0+0x57a/0xbf0 drivers/tty/vt/vt.c:3960
 vt_bind drivers/tty/vt/vt.c:4116 [inline]
 store_bind+0x61d/0x760 drivers/tty/vt/vt.c:4188
 dev_attr_store+0x58/0x80 drivers/base/core.c:2437
 sysfs_kf_write+0xf2/0x150 fs/sysfs/file.c:142
 kernfs_fop_write_iter+0x3af/0x570 fs/kernfs/file.c:352
 iter_file_splice_write+0xa24/0x12b0 fs/splice.c:738
 do_splice_from fs/splice.c:938 [inline]
 direct_splice_actor+0x192/0x6c0 fs/splice.c:1161
 splice_direct_to_actor+0x345/0xa30 fs/splice.c:1105
 do_splice_direct_actor fs/splice.c:1204 [inline]
 do_splice_direct+0x174/0x240 fs/splice.c:1230
 do_sendfile+0xb06/0xe50 fs/read_write.c:1370
 __do_sys_sendfile64 fs/read_write.c:1431 [inline]
 __se_sys_sendfile64 fs/read_write.c:1417 [inline]
 __x64_sys_sendfile64+0x1d8/0x220 fs/read_write.c:1417
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7073f8f7c9
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:00007f7074e67038 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 00007f70741e6090 RCX: 00007f7073f8f7c9
RDX: 0000000000000000 RSI: 000000000000000a RDI: 0000000000000004
RBP: 00007f7074013f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000007 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f70741e6128 R14: 00007f70741e6090 R15: 00007ffcf2a68b28
 </TASK>

The buggy address belongs to the physical page:
page: refcount:0 mapcount:0 mapping:0000000000000000 index:0xffff888043c56f00 pfn:0x43c56
flags: 0xfff00000000000(node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000000 dead000000000100 dead000000000122 0000000000000000
raw: ffff888043c56f00 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as freed
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x2dc2(GFP_KERNEL|__GFP_HIGHMEM|__GFP_ZERO|__GFP_NOWARN), pid 19553, tgid 19550 (syz.2.2907), ts 855080142810, free_ts 855480757526
 set_page_owner include/linux/page_owner.h:32 [inline]
 post_alloc_hook+0x1af/0x220 mm/page_alloc.c:1857
 prep_new_page mm/page_alloc.c:1865 [inline]
 get_page_from_freelist+0xd0b/0x31a0 mm/page_alloc.c:3915
 __alloc_frozen_pages_noprof+0x25f/0x2430 mm/page_alloc.c:5210
 __alloc_pages_noprof mm/page_alloc.c:5244 [inline]
 alloc_pages_bulk_noprof+0x77a/0x1410 mm/page_alloc.c:5164
 alloc_pages_bulk_mempolicy_noprof+0x244/0x12a0 mm/mempolicy.c:2794
 vm_area_alloc_pages mm/vmalloc.c:3693 [inline]
 __vmalloc_area_node mm/vmalloc.c:3863 [inline]
 __vmalloc_node_range_noprof+0xb98/0x16b0 mm/vmalloc.c:4051
 __vmalloc_node_noprof+0xad/0xf0 mm/vmalloc.c:4111
 n_tty_open+0x1a/0x170 drivers/tty/n_tty.c:1890
 tty_ldisc_open+0x9f/0x120 drivers/tty/tty_ldisc.c:432
 tty_ldisc_setup+0x87/0x100 drivers/tty/tty_ldisc.c:755
 tty_init_dev.part.0+0x1ec/0x500 drivers/tty/tty_io.c:1431
 tty_init_dev+0x60/0x80 drivers/tty/tty_io.c:1397
 ptmx_open drivers/tty/pty.c:799 [inline]
 ptmx_open+0x15e/0x3c0 drivers/tty/pty.c:765
 chrdev_open+0x234/0x6a0 fs/char_dev.c:414
 do_dentry_open+0x748/0x1590 fs/open.c:962
 vfs_open+0x82/0x3f0 fs/open.c:1094
page last free pid 19550 tgid 19550 stack trace:
 reset_page_owner include/linux/page_owner.h:25 [inline]
 free_pages_prepare mm/page_alloc.c:1406 [inline]
 __free_frozen_pages+0x7df/0x1170 mm/page_alloc.c:2943
 vfree+0x1fd/0xb50 mm/vmalloc.c:3466
 n_tty_close+0xcd/0x160 drivers/tty/n_tty.c:1873
 tty_ldisc_close+0x114/0x1a0 drivers/tty/tty_ldisc.c:455
 tty_ldisc_kill+0x8e/0x150 drivers/tty/tty_ldisc.c:613
 tty_ldisc_hangup+0x365/0x730 drivers/tty/tty_ldisc.c:729
 __tty_hangup.part.0+0x3fe/0x8c0 drivers/tty/tty_io.c:621
 __tty_hangup drivers/tty/tty_io.c:688 [inline]
 tty_vhangup drivers/tty/tty_io.c:691 [inline]
 tty_vhangup+0x21/0x30 drivers/tty/tty_io.c:688
 pty_close+0x3ca/0x540 drivers/tty/pty.c:77
 tty_release+0x3af/0x1470 drivers/tty/tty_io.c:1745
 __fput+0x402/0xb70 fs/file_table.c:468
 task_work_run+0x150/0x240 kernel/task_work.c:233
 resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
 __exit_to_user_mode_loop kernel/entry/common.c:44 [inline]
 exit_to_user_mode_loop+0xfb/0x540 kernel/entry/common.c:75
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode_work include/linux/entry-common.h:159 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:194 [inline]
 do_syscall_64+0x4ee/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
 ffff888043c56280: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888043c56300: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
>ffff888043c56380: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                                           ^
 ffff888043c56400: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff888043c56480: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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