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BUG: KASAN: use-after-free in __fb_pad_aligned_buffer include/linux/fb.h:663 [inline]
BUG: KASAN: use-after-free in bit_putcs_aligned drivers/video/fbdev/core/bitblit.c:96 [inline]
BUG: KASAN: use-after-free in bit_putcs+0xab7/0xc30 drivers/video/fbdev/core/bitblit.c:185
Read of size 1 at addr ffff88808b067730 by task syz-executor.4/15727

CPU: 0 PID: 15727 Comm: syz-executor.4 Not tainted 4.14.193-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:1301
 do_update_region+0x34b/0x5b0 drivers/tty/vt/vt.c:373
 redraw_screen+0x56e/0x790 drivers/tty/vt/vt.c:705
 vc_do_resize+0xc20/0xe30 drivers/tty/vt/vt.c:973
 vt_ioctl+0x19f7/0x1ea0 drivers/tty/vt/vt_ioctl.c:901
 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
RIP: 0033:0x45d239
RSP: 002b:00007fbb9d0f9c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 000000000001c340 RCX: 000000000045d239
RDX: 0000000020000000 RSI: 000000000000560a RDI: 0000000000000003
RBP: 000000000118cf80 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c
R13: 00007ffd50e040ef R14: 00007fbb9d0fa9c0 R15: 000000000118cf4c

Allocated by task 15049:
 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
 kmem_cache_alloc_trace+0x131/0x3d0 mm/slab.c:3618
 kmalloc include/linux/slab.h:488 [inline]
 kzalloc include/linux/slab.h:661 [inline]
 find_css_set+0x618/0x16c0 kernel/cgroup/cgroup.c:1097
 cgroup_migrate_prepare_dst+0xff/0x740 kernel/cgroup/cgroup.c:2476
 cgroup_attach_task+0x2f2/0x800 kernel/cgroup/cgroup.c:2589
 cgroup_attach_task_all+0xba/0x140 kernel/cgroup/cgroup-v1.c:69
 kvm_vm_worker_thread+0xd3/0x250 arch/x86/kvm/../../../virt/kvm/kvm_main.c:4235
 kthread+0x30d/0x420 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Freed by task 17:
 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
 __rcu_reclaim kernel/rcu/rcu.h:190 [inline]
 rcu_do_batch kernel/rcu/tree.c:2699 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2962 [inline]
 __rcu_process_callbacks kernel/rcu/tree.c:2929 [inline]
 rcu_process_callbacks+0x88b/0x1180 kernel/rcu/tree.c:2946
 __do_softirq+0x254/0xa1d kernel/softirq.c:288

The buggy address belongs to the object at ffff88808b0676c0
 which belongs to the cache kmalloc-1024 of size 1024
The buggy address is located 112 bytes inside of
 1024-byte region [ffff88808b0676c0, ffff88808b067ac0)
The buggy address belongs to the page:
page:ffffea00022c1980 count:1 mapcount:0 mapping:ffff88808b066040 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffff88808b066040 0000000000000000 0000000100000007
raw: ffffea0002309c20 ffffea0002948b20 ffff88812fe52ac0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88808b067600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88808b067680: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff88808b067700: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff88808b067780: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88808b067800: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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