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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+0xab7/0xc30 drivers/video/fbdev/core/bitblit.c:185
Read of size 1 at addr ffff88805af177b0 by task syz-executor.0/19679

CPU: 1 PID: 19679 Comm: syz-executor.0 Not tainted 4.14.206-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+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
 kasan_report mm/kasan/report.c:409 [inline]
 __asan_report_load1_noabort+0x68/0x70 mm/kasan/report.c:427
 __fb_pad_aligned_buffer include/linux/fb.h:663 [inline]
 bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline]
 bit_putcs+0xab7/0xc30 drivers/video/fbdev/core/bitblit.c:185
 fbcon_putcs+0x2fe/0x480 drivers/video/fbdev/core/fbcon.c:1247
 con_flush drivers/tty/vt/vt.c:2206 [inline]
 do_con_write+0xaf6/0x19b0 drivers/tty/vt/vt.c:2456
 con_write+0x21/0xa0 drivers/tty/vt/vt.c:2805
 process_output_block drivers/tty/n_tty.c:595 [inline]
 n_tty_write+0x352/0xda0 drivers/tty/n_tty.c:2333
 do_tty_write drivers/tty/tty_io.c:959 [inline]
 tty_write+0x410/0x740 drivers/tty/tty_io.c:1043
 do_loop_readv_writev fs/read_write.c:698 [inline]
 do_loop_readv_writev fs/read_write.c:682 [inline]
 do_iter_write+0x3da/0x550 fs/read_write.c:956
 vfs_writev+0x125/0x290 fs/read_write.c:999
 do_writev+0xfc/0x2c0 fs/read_write.c:1034
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45deb9
RSP: 002b:00007fae62e6dc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000014
RAX: ffffffffffffffda RBX: 000000000003b980 RCX: 000000000045deb9
RDX: 000000000000000a RSI: 0000000020001580 RDI: 0000000000000003
RBP: 000000000118bf60 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118bf2c
R13: 00007ffc2e95651f R14: 00007fae62e6e9c0 R15: 000000000118bf2c

Allocated by task 12501:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 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+0x2fb/0x7c0 drivers/video/fbdev/core/fbcon.c:2456
 con_font_set drivers/tty/vt/vt.c:4190 [inline]
 con_font_op+0x9e2/0xd90 drivers/tty/vt/vt.c:4234
 vt_ioctl+0xd5d/0x1d50 drivers/tty/vt/vt_ioctl.c:938
 tty_ioctl+0x50f/0x13c0 drivers/tty/tty_io.c:2661
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x75a/0xff0 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 4625:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 do_delayed_call include/linux/delayed_call.h:28 [inline]
 generic_readlink fs/namei.c:4735 [inline]
 vfs_readlink+0x11d/0x3b0 fs/namei.c:4765
 SYSC_readlinkat fs/stat.c:406 [inline]
 SyS_readlinkat+0x1e8/0x270 fs/stat.c:382
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff88805af16940
 which belongs to the cache kmalloc-4096 of size 4096
The buggy address is located 3696 bytes inside of
 4096-byte region [ffff88805af16940, ffff88805af17940)
The buggy address belongs to the page:
page:ffffea00016bc580 count:1 mapcount:0 mapping:ffff88805af16940 index:0x0 compound_mapcount: 0
flags: 0xfff00000008100(slab|head)
raw: 00fff00000008100 ffff88805af16940 0000000000000000 0000000100000001
raw: ffffea00027045a0 ffffea000195b520 ffff88813fe82dc0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88805af17680: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805af17700: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88805af17780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                     ^
 ffff88805af17800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805af17880: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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