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BUG: KASAN: slab-out-of-bounds in fbcon_get_font+0x58a/0x5b0 drivers/video/fbdev/core/fbcon.c:2462
Read of size 1 at addr ffff8880928aecd0 by task syz-executor.0/16737

CPU: 1 PID: 16737 Comm: syz-executor.0 Not tainted 4.19.121-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:77 [inline]
 dump_stack+0x188/0x20d lib/dump_stack.c:118
 print_address_description.cold+0x7c/0x212 mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report mm/kasan/report.c:412 [inline]
 kasan_report.cold+0x88/0x2b9 mm/kasan/report.c:396
 fbcon_get_font+0x58a/0x5b0 drivers/video/fbdev/core/fbcon.c:2462
 con_font_get drivers/tty/vt/vt.c:4432 [inline]
 con_font_op+0x1f7/0x1130 drivers/tty/vt/vt.c:4591
 do_fontx_ioctl drivers/tty/vt/vt_ioctl.c:273 [inline]
 vt_ioctl+0x1d25/0x2500 drivers/tty/vt/vt_ioctl.c:945
 tty_ioctl+0x7a1/0x1420 drivers/tty/tty_io.c:2669
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xcda/0x12e0 fs/ioctl.c:688
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45c829
Code: 0d b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 db b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007f6518decc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00000000004e94a0 RCX: 000000000045c829
RDX: 0000000020000000 RSI: 0000000000004b6b RDI: 0000000000000003
RBP: 000000000078bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000423 R14: 00000000004c6c3b R15: 00007f6518ded6d4

Allocated by task 14975:
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc mm/kasan/kasan.c:553 [inline]
 kasan_kmalloc+0xbf/0xe0 mm/kasan/kasan.c:531
 __do_kmalloc mm/slab.c:3727 [inline]
 __kmalloc+0x15b/0x770 mm/slab.c:3736
 kmalloc include/linux/slab.h:520 [inline]
 fbcon_set_font+0x331/0x870 drivers/video/fbdev/core/fbcon.c:2644
 con_font_set drivers/tty/vt/vt.c:4524 [inline]
 con_font_op+0xd3e/0x1130 drivers/tty/vt/vt.c:4589
 vt_ioctl+0x16f1/0x2500 drivers/tty/vt/vt_ioctl.c:980
 tty_ioctl+0x7a1/0x1420 drivers/tty/tty_io.c:2669
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:501 [inline]
 do_vfs_ioctl+0xcda/0x12e0 fs/ioctl.c:688
 ksys_ioctl+0x9b/0xc0 fs/ioctl.c:705
 __do_sys_ioctl fs/ioctl.c:712 [inline]
 __se_sys_ioctl fs/ioctl.c:710 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:710
 do_syscall_64+0xf9/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8880928ae0c0
 which belongs to the cache kmalloc-4096 of size 4096
The buggy address is located 3088 bytes inside of
 4096-byte region [ffff8880928ae0c0, ffff8880928af0c0)
The buggy address belongs to the page:
page:ffffea00024a2b80 count:1 mapcount:0 mapping:ffff88812c39cdc0 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffffea00012e3188 ffffea0002582688 ffff88812c39cdc0
raw: 0000000000000000 ffff8880928ae0c0 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880928aeb80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880928aec00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880928aec80: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
                                                 ^
 ffff8880928aed00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880928aed80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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