8021q: adding VLAN 0 to HW filter on device batadv0
audit: type=1400 audit(1575484102.802:38): avc:  denied  { associate } for  pid=7749 comm="syz-executor.0" name="syz0" scontext=unconfined_u:object_r:unlabeled_t:s0 tcontext=system_u:object_r:unlabeled_t:s0 tclass=filesystem permissive=1
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BUG: KASAN: slab-out-of-bounds in vcs_scr_readw+0xc2/0xd0 drivers/tty/vt/vt.c:4618
Read of size 2 at addr ffff8880857c63c0 by task syz-executor.0/7758

CPU: 0 PID: 7758 Comm: syz-executor.0 Not tainted 4.19.87-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+0x197/0x210 lib/dump_stack.c:118
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report mm/kasan/report.c:412 [inline]
 kasan_report.cold+0x8c/0x2ba mm/kasan/report.c:396
 __asan_report_load2_noabort+0x14/0x20 mm/kasan/report.c:431
 vcs_scr_readw+0xc2/0xd0 drivers/tty/vt/vt.c:4618
 vcs_write+0x646/0xcf0 drivers/tty/vt/vc_screen.c:526
 __vfs_write+0x114/0x810 fs/read_write.c:485
 vfs_write+0x20c/0x560 fs/read_write.c:549
 ksys_write+0x14f/0x2d0 fs/read_write.c:599
 __do_sys_write fs/read_write.c:611 [inline]
 __se_sys_write fs/read_write.c:608 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:608
 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x45a679
Code: ad b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 7b b6 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fbafbf8bc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 000000000045a679
RDX: 00000000ffffff78 RSI: 00000000200000c0 RDI: 0000000000000004
RBP: 000000000075c070 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fbafbf8c6d4
R13: 00000000004cba69 R14: 00000000004e5670 R15: 00000000ffffffff

Allocated by task 7709:
 save_stack+0x45/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc mm/kasan/kasan.c:553 [inline]
 kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:531
 __do_kmalloc mm/slab.c:3727 [inline]
 __kmalloc+0x15d/0x750 mm/slab.c:3736
 kmalloc include/linux/slab.h:520 [inline]
 kzalloc include/linux/slab.h:709 [inline]
 vc_allocate drivers/tty/vt/vt.c:1101 [inline]
 vc_allocate+0x3f5/0x760 drivers/tty/vt/vt.c:1069
 con_install+0x52/0x410 drivers/tty/vt/vt.c:3204
 tty_driver_install_tty drivers/tty/tty_io.c:1226 [inline]
 tty_init_dev drivers/tty/tty_io.c:1339 [inline]
 tty_init_dev+0xf7/0x460 drivers/tty/tty_io.c:1316
 tty_open_by_driver drivers/tty/tty_io.c:1981 [inline]
 tty_open+0x4bf/0xb70 drivers/tty/tty_io.c:2029
 chrdev_open+0x245/0x6b0 fs/char_dev.c:423
 do_dentry_open+0x4c3/0x1210 fs/open.c:796
 vfs_open+0xa0/0xd0 fs/open.c:905
 do_last fs/namei.c:3418 [inline]
 path_openat+0x10d7/0x45e0 fs/namei.c:3534
 do_filp_open+0x1a1/0x280 fs/namei.c:3564
 do_sys_open+0x3fe/0x550 fs/open.c:1088
 __do_sys_open fs/open.c:1106 [inline]
 __se_sys_open fs/open.c:1101 [inline]
 __x64_sys_open+0x7e/0xc0 fs/open.c:1101
 do_syscall_64+0xfd/0x620 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8880857c5100
 which belongs to the cache kmalloc-8192 of size 8192
The buggy address is located 4800 bytes inside of
 8192-byte region [ffff8880857c5100, ffff8880857c7100)
The buggy address belongs to the page:
page:ffffea000215f100 count:1 mapcount:0 mapping:ffff88812c315080 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffffea0002151508 ffffea00021b8108 ffff88812c315080
raw: 0000000000000000 ffff8880857c5100 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880857c6280: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8880857c6300: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8880857c6380: 00 00 00 00 00 00 00 00 fc fc fc fc fc fc fc fc
                                           ^
 ffff8880857c6400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8880857c6480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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