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BUG: KASAN: use-after-free in memcpy include/linux/string.h:372 [inline]
BUG: KASAN: use-after-free in soft_cursor+0x442/0xa50 drivers/video/fbdev/core/softcursor.c:70
Read of size 9 at addr ffff888083db12fe by task syz-executor.0/20264

CPU: 0 PID: 20264 Comm: syz-executor.0 Not tainted 4.14.198-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+0x6f/0x7b mm/kasan/report.c:409
 memcpy+0x20/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:372 [inline]
 soft_cursor+0x442/0xa50 drivers/video/fbdev/core/softcursor.c:70
 bit_cursor+0x1056/0x1620 drivers/video/fbdev/core/bitblit.c:386
 fbcon_cursor+0x4b1/0x6a0 drivers/video/fbdev/core/fbcon.c:1350
 fbcon_scroll+0x2b7/0x33b0 drivers/video/fbdev/core/fbcon.c:1827
 con_scroll+0x2c5/0x360 drivers/tty/vt/vt.c:327
 lf+0x226/0x270 drivers/tty/vt/vt.c:1141
 do_con_write+0xf9b/0x19b0 drivers/tty/vt/vt.c:2414
 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
 __vfs_write+0xe4/0x630 fs/read_write.c:480
 __kernel_write+0xf5/0x330 fs/read_write.c:501
 write_pipe_buf+0x143/0x1c0 fs/splice.c:797
 splice_from_pipe_feed fs/splice.c:502 [inline]
 __splice_from_pipe+0x326/0x7a0 fs/splice.c:626
 splice_from_pipe fs/splice.c:661 [inline]
 default_file_splice_write+0xc5/0x150 fs/splice.c:809
 do_splice_from fs/splice.c:851 [inline]
 direct_splice_actor+0x115/0x160 fs/splice.c:1018
 splice_direct_to_actor+0x27c/0x730 fs/splice.c:973
 do_splice_direct+0x164/0x210 fs/splice.c:1061
 do_sendfile+0x47f/0xb30 fs/read_write.c:1441
 SYSC_sendfile64 fs/read_write.c:1496 [inline]
 SyS_sendfile64+0x9b/0x110 fs/read_write.c:1488
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45d5f9
RSP: 002b:00007f1ac369fc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000028
RAX: ffffffffffffffda RBX: 0000000000027a00 RCX: 000000000045d5f9
RDX: 0000000020000040 RSI: 0000000000000003 RDI: 0000000000000005
RBP: 000000000118cf88 R08: 0000000000000000 R09: 0000000000000000
R10: 000000000000a808 R11: 0000000000000246 R12: 000000000118cf4c
R13: 00007ffd7993db6f R14: 00007f1ac36a09c0 R15: 000000000118cf4c

Allocated by task 19127:
 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]
 kzalloc include/linux/slab.h:661 [inline]
 __register_sysctl_table+0xfd/0xf90 fs/proc/proc_sysctl.c:1304
 __addrconf_sysctl_register+0x1c8/0x380 net/ipv6/addrconf.c:6419
 addrconf_sysctl_register+0x10d/0x1a0 net/ipv6/addrconf.c:6466
 ipv6_add_dev.part.0+0x9b7/0xf70 net/ipv6/addrconf.c:460
 ipv6_add_dev net/ipv6/addrconf.c:3520 [inline]
 addrconf_notify+0x85d/0x1b80 net/ipv6/addrconf.c:3373
 notifier_call_chain+0x108/0x1a0 kernel/notifier.c:93
 call_netdevice_notifiers_info net/core/dev.c:1667 [inline]
 call_netdevice_notifiers net/core/dev.c:1683 [inline]
 register_netdevice+0xb98/0xe40 net/core/dev.c:7691
 __tun_chr_ioctl.isra.0+0x15a8/0x3310 drivers/net/tun.c:2120
 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 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 ffff888083db1280
 which belongs to the cache kmalloc-2048 of size 2048
The buggy address is located 126 bytes inside of
 2048-byte region [ffff888083db1280, ffff888083db1a80)
The buggy address belongs to the page:
page:ffffea00020f6c00 count:1 mapcount:0 mapping:ffff888083db0180 index:0xffff888083db0180 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffff888083db0180 ffff888083db0180 0000000100000001
raw: ffffea0001d05fa0 ffffea0000680ca0 ffff88812fe50c40 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888083db1180: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888083db1200: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888083db1280: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                                                ^
 ffff888083db1300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888083db1380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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