==================================================================
BUG: KASAN: slab-out-of-bounds in __fb_pad_aligned_buffer include/linux/fb.h:663 [inline]
BUG: KASAN: slab-out-of-bounds in bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline]
BUG: KASAN: slab-out-of-bounds in bit_putcs+0xa8a/0xc00 drivers/video/fbdev/core/bitblit.c:185
Read of size 1 at addr ffff88805ad01100 by task syz-executor.3/2811

CPU: 1 PID: 2811 Comm: syz-executor.3 Not tainted 4.14.184-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1dc mm/kasan/report.c:252
 kasan_report_error mm/kasan/report.c:351 [inline]
 kasan_report mm/kasan/report.c:409 [inline]
 kasan_report.cold+0xa9/0x2b9 mm/kasan/report.c:393
 __fb_pad_aligned_buffer include/linux/fb.h:663 [inline]
 bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline]
 bit_putcs+0xa8a/0xc00 drivers/video/fbdev/core/bitblit.c:185
 fbcon_putcs+0x3bb/0x480 drivers/video/fbdev/core/fbcon.c:1301
 con_flush drivers/tty/vt/vt.c:2199 [inline]
 do_con_write.part.0+0xc27/0x1a20 drivers/tty/vt/vt.c:2446
 do_con_write drivers/tty/vt/vt.c:2218 [inline]
 con_write+0x33/0xc0 drivers/tty/vt/vt.c:2798
 process_output_block drivers/tty/n_tty.c:595 [inline]
 n_tty_write+0x375/0xe20 drivers/tty/n_tty.c:2333
 do_tty_write drivers/tty/tty_io.c:959 [inline]
 tty_write+0x3f1/0x6e0 drivers/tty/tty_io.c:1043
 __vfs_write+0xe4/0x630 fs/read_write.c:480
 vfs_write+0x17f/0x4d0 fs/read_write.c:544
 SYSC_write fs/read_write.c:590 [inline]
 SyS_write+0xf2/0x210 fs/read_write.c:582
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45cb29
RSP: 002b:00007f23ae146c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 000000000050de40 RCX: 000000000045cb29
RDX: 0000000000001006 RSI: 0000000020001380 RDI: 0000000000000004
RBP: 000000000078bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00000000ffffffff
R13: 0000000000000d20 R14: 00000000004cf7bc R15: 00007f23ae1476d4

Allocated by task 23427:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc.part.0+0x4f/0xd0 mm/kasan/kasan.c:551
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc+0x15a/0x400 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 fbcon_set_font+0x2f8/0x7c0 drivers/video/fbdev/core/fbcon.c:2621
 con_font_set drivers/tty/vt/vt.c:4182 [inline]
 con_font_op+0xb73/0xf70 drivers/tty/vt/vt.c:4247
 vt_ioctl+0x736/0x1f20 drivers/tty/vt/vt_ioctl.c:928
 tty_ioctl+0x6c9/0x1220 drivers/tty/tty_io.c:2661
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xfe0 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x7f/0xb0 fs/ioctl.c:692
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 22640:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xaf/0x190 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcb/0x260 mm/slab.c:3815
 kvfree+0x45/0x50 mm/util.c:416
 __free_fdtable+0x2d/0x70 fs/file.c:36
 put_files_struct fs/file.c:425 [inline]
 put_files_struct+0x239/0x2d0 fs/file.c:418
 exit_files+0x7e/0xa0 fs/file.c:450
 do_exit+0x9d0/0x2ae0 kernel/exit.c:853
 do_group_exit+0x100/0x2e0 kernel/exit.c:955
 get_signal+0x385/0x1c90 kernel/signal.c:2423
 do_signal+0x7c/0x15d0 arch/x86/kernel/signal.c:814
 exit_to_usermode_loop+0x160/0x200 arch/x86/entry/common.c:160
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff88805ad00940
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 1984 bytes inside of
 2048-byte region [ffff88805ad00940, ffff88805ad01140)
The buggy address belongs to the page:
page:ffffea00016b4000 count:1 mapcount:0 mapping:ffff88805ad000c0 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffff88805ad000c0 0000000000000000 0000000100000003
raw: ffffea000166b7a0 ffffea0001801820 ffff8880aa800c40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88805ad01000: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
 ffff88805ad01080: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88805ad01100: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                   ^
 ffff88805ad01180: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
 ffff88805ad01200: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
==================================================================