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BUG: KASAN: vmalloc-out-of-bounds in sys_imageblit+0xff5/0x1e40
Write of size 8 at addr ffffc9000662d280 by task syz.3.2589/19867

CPU: 1 UID: 0 PID: 19867 Comm: syz.3.2589 Tainted: G             L      syzkaller #0 PREEMPT(full) 
Tainted: [L]=SOFTLOCKUP
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
Call Trace:
 <TASK>
 dump_stack_lvl+0xe8/0x150
 print_address_description+0x55/0x1e0
 print_report+0x58/0x70
 kasan_report+0x117/0x150
 sys_imageblit+0xff5/0x1e40
 drm_fbdev_shmem_defio_imageblit+0x2c/0x110
 soft_cursor+0xa0e/0xc40
 bit_cursor+0x11c3/0x1970
 hide_cursor+0xd3/0x490
 do_con_write+0x1bb/0x5500
 con_write+0x27/0x290
 n_tty_write+0xd49/0x11e0
 file_tty_write+0x509/0x9c0
 vfs_write+0x612/0xba0
 ksys_write+0x150/0x270
 do_syscall_64+0x174/0x580
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fc27bf9e159
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:00007fc27cebc028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007fc27c226270 RCX: 00007fc27bf9e159
RDX: 0000000000001006 RSI: 00002000000005c0 RDI: 0000000000000022
RBP: 00007fc27c03506b R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fc27c226308 R14: 00007fc27c226270 R15: 00007ffd40796a08
 </TASK>

The buggy address belongs to a vmalloc virtual mapping
Memory state around the buggy address:
 ffffc9000662d180: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc9000662d200: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>ffffc9000662d280: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
                   ^
 ffffc9000662d300: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
 ffffc9000662d380: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
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