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BUG: KASAN: use-after-free in fbcon_get_font+0x2f8/0x770 drivers/video/fbdev/core/fbcon.c:2293
Write of size 16369 at addr ffff88806fb6c013 by task syz-executor.0/5553

CPU: 0 PID: 5553 Comm: syz-executor.0 Not tainted 6.2.0-rc4-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/16/2023
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x5b/0x81 lib/dump_stack.c:106
 print_address_description mm/kasan/report.c:306 [inline]
 print_report+0x15e/0x45d mm/kasan/report.c:417
 kasan_report+0xbf/0x1f0 mm/kasan/report.c:517
 check_region_inline mm/kasan/generic.c:183 [inline]
 kasan_check_range+0x141/0x190 mm/kasan/generic.c:189
 memset+0x24/0x50 mm/kasan/shadow.c:44
 fbcon_get_font+0x2f8/0x770 drivers/video/fbdev/core/fbcon.c:2293
 con_font_get drivers/tty/vt/vt.c:4556 [inline]
 con_font_op+0x1a8/0xd00 drivers/tty/vt/vt.c:4670
 vt_k_ioctl drivers/tty/vt/vt_ioctl.c:474 [inline]
 vt_ioctl+0x1612/0x24c0 drivers/tty/vt/vt_ioctl.c:752
 tty_ioctl+0x684/0x1250 drivers/tty/tty_io.c:2777
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x123/0x190 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fcaa448c0f9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 19 00 00 90 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fcaa52a6168 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007fcaa45abf80 RCX: 00007fcaa448c0f9
RDX: 0000000020000000 RSI: 0000000000004b72 RDI: 0000000000000003
RBP: 00007fcaa44e7ae9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd4110c59f R14: 00007fcaa52a6300 R15: 0000000000022000
 </TASK>

The buggy address belongs to the physical page:
page:ffffea0001bed800 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x6fb60
head:ffffea0001bed800 order:4 compound_mapcount:0 subpages_mapcount:0 compound_pincount:0
flags: 0xfff00000010000(head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010000 0000000000000000 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 4, migratetype Unmovable, gfp_mask 0x140cc0(GFP_USER|__GFP_COMP), pid 5553, tgid 5552 (syz-executor.0), ts 55410633843, free_ts 6323370375
 prep_new_page mm/page_alloc.c:2531 [inline]
 get_page_from_freelist+0x119c/0x2ce0 mm/page_alloc.c:4283
 __alloc_pages+0x1cb/0x5b0 mm/page_alloc.c:5549
 __alloc_pages_node include/linux/gfp.h:237 [inline]
 alloc_pages_node include/linux/gfp.h:260 [inline]
 __kmalloc_large_node+0x85/0x160 mm/slab_common.c:1113
 kmalloc_large+0x1c/0x70 mm/slab_common.c:1130
 kmalloc include/linux/slab.h:577 [inline]
 con_font_get drivers/tty/vt/vt.c:4546 [inline]
 con_font_op+0xf3/0xd00 drivers/tty/vt/vt.c:4670
 vt_k_ioctl drivers/tty/vt/vt_ioctl.c:474 [inline]
 vt_ioctl+0x1612/0x24c0 drivers/tty/vt/vt_ioctl.c:752
 tty_ioctl+0x684/0x1250 drivers/tty/tty_io.c:2777
 vfs_ioctl fs/ioctl.c:51 [inline]
 __do_sys_ioctl fs/ioctl.c:870 [inline]
 __se_sys_ioctl fs/ioctl.c:856 [inline]
 __x64_sys_ioctl+0x123/0x190 fs/ioctl.c:856
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
page last free stack trace:
 reset_page_owner include/linux/page_owner.h:24 [inline]
 free_pages_prepare mm/page_alloc.c:1446 [inline]
 free_pcp_prepare+0x66a/0xc20 mm/page_alloc.c:1496
 free_unref_page_prepare mm/page_alloc.c:3369 [inline]
 free_unref_page+0x1d/0x490 mm/page_alloc.c:3464
 free_contig_range+0xb5/0x180 mm/page_alloc.c:9485
 destroy_args+0x7e/0x509 mm/debug_vm_pgtable.c:998
 debug_vm_pgtable+0x1ef5/0x1f79 mm/debug_vm_pgtable.c:1318
 do_one_initcall+0xf8/0x560 init/main.c:1306
 do_initcall_level init/main.c:1379 [inline]
 do_initcalls init/main.c:1395 [inline]
 do_basic_setup init/main.c:1414 [inline]
 kernel_init_freeable+0x5df/0x639 init/main.c:1634
 kernel_init+0x18/0x130 init/main.c:1522
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308

Memory state around the buggy address:
 ffff88806fb6ff00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88806fb6ff80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88806fb70000: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
                   ^
 ffff88806fb70080: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
 ffff88806fb70100: ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff ff
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