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BUG: KASAN: slab-out-of-bounds in fbcon_get_font+0x689/0x6f0 drivers/video/fbdev/core/fbcon.c:2491
Read of size 1 at addr ffff88804bd76c10 by task syz-executor.3/9494

CPU: 0 PID: 9494 Comm: syz-executor.3 Not tainted 5.8.0-rc6-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+0x18f/0x20d lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xae/0x436 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x1f/0x37 mm/kasan/report.c:530
 fbcon_get_font+0x689/0x6f0 drivers/video/fbdev/core/fbcon.c:2491
 con_font_get drivers/tty/vt/vt.c:4479 [inline]
 con_font_op+0x1f5/0x1110 drivers/tty/vt/vt.c:4638
 vt_ioctl+0x1180/0x2670 drivers/tty/vt/vt_ioctl.c:928
 tty_ioctl+0x1019/0x15f0 drivers/tty/tty_io.c:2656
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9
RIP: 0033:0x45c1f9
Code: Bad RIP value.
RSP: 002b:00007f23e4c7ec78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000000f4c0 RCX: 000000000045c1f9
RDX: 0000000020000040 RSI: 0000000000004b60 RDI: 0000000000000003
RBP: 000000000078bf40 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000078bf0c
R13: 00007ffc354651ef R14: 00007f23e4c7f9c0 R15: 000000000078bf0c

Allocated by task 8316:
 save_stack+0x1b/0x40 mm/kasan/common.c:48
 set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xc2/0xd0 mm/kasan/common.c:494
 __do_kmalloc mm/slab.c:3656 [inline]
 __kmalloc+0x17a/0x340 mm/slab.c:3665
 kmalloc include/linux/slab.h:560 [inline]
 fbcon_set_font+0x34f/0x8b0 drivers/video/fbdev/core/fbcon.c:2673
 con_font_set drivers/tty/vt/vt.c:4571 [inline]
 con_font_op+0xd25/0x1110 drivers/tty/vt/vt.c:4636
 vt_ioctl+0x16dc/0x2670 drivers/tty/vt/vt_ioctl.c:980
 tty_ioctl+0x1019/0x15f0 drivers/tty/tty_io.c:2656
 vfs_ioctl fs/ioctl.c:48 [inline]
 ksys_ioctl+0x11a/0x180 fs/ioctl.c:753
 __do_sys_ioctl fs/ioctl.c:762 [inline]
 __se_sys_ioctl fs/ioctl.c:760 [inline]
 __x64_sys_ioctl+0x6f/0xb0 fs/ioctl.c:760
 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:384
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff88804bd70000
 which belongs to the cache kmalloc-32k of size 32768
The buggy address is located 27664 bytes inside of
 32768-byte region [ffff88804bd70000, ffff88804bd78000)
The buggy address belongs to the page:
page:ffffea00012f5c00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 head:ffffea00012f5c00 order:4 compound_mapcount:0 compound_pincount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea00013d8408 ffff8880aa001d50 ffff8880aa002540
raw: 0000000000000000 ffff88804bd70000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88804bd76b00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88804bd76b80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88804bd76c00: 00 00 fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                         ^
 ffff88804bd76c80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88804bd76d00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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