sp0: Synchronizing with TNC
==================================================================
BUG: KASAN: slab-out-of-bounds in decode_data.part.0+0x23b/0x270 drivers/net/hamradio/6pack.c:874
Write of size 1 at addr ffff88805ca53a8e by task kworker/u4:3/177

CPU: 1 PID: 177 Comm: kworker/u4:3 Not tainted 4.14.171-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: events_unbound flush_to_ldisc
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x142/0x197 lib/dump_stack.c:58
 print_address_description.cold+0x7c/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+0xa9/0x2af mm/kasan/report.c:393
 __asan_report_store1_noabort+0x17/0x20 mm/kasan/report.c:432
 decode_data.part.0+0x23b/0x270 drivers/net/hamradio/6pack.c:874
 decode_data drivers/net/hamradio/6pack.c:1004 [inline]
 sixpack_decode drivers/net/hamradio/6pack.c:1007 [inline]
 sixpack_receive_buf drivers/net/hamradio/6pack.c:458 [inline]
 sixpack_receive_buf+0xaf7/0x1170 drivers/net/hamradio/6pack.c:435
 tty_ldisc_receive_buf+0x14d/0x1a0 drivers/tty/tty_buffer.c:459
 tty_port_default_receive_buf+0x73/0xa0 drivers/tty/tty_port.c:37
 receive_buf drivers/tty/tty_buffer.c:475 [inline]
 flush_to_ldisc+0x1ec/0x400 drivers/tty/tty_buffer.c:527
 process_one_work+0x863/0x1600 kernel/workqueue.c:2114
 worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
 kthread+0x319/0x430 kernel/kthread.c:232
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404

Allocated by task 21056:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc mm/kasan/kasan.c:551 [inline]
 kasan_kmalloc+0xce/0xf0 mm/kasan/kasan.c:529
 __do_kmalloc_node mm/slab.c:3682 [inline]
 __kmalloc_node+0x51/0x80 mm/slab.c:3689
 kmalloc_node include/linux/slab.h:530 [inline]
 kvmalloc_node+0x4e/0xe0 mm/util.c:397
 kvmalloc include/linux/mm.h:531 [inline]
 kvzalloc include/linux/mm.h:539 [inline]
 alloc_netdev_mqs+0x7b/0xbc0 net/core/dev.c:8097
 sixpack_open+0xdf/0xc85 drivers/net/hamradio/6pack.c:572
 tty_ldisc_open.isra.0+0x73/0xb0 drivers/tty/tty_ldisc.c:481
 tty_set_ldisc+0x28e/0x600 drivers/tty/tty_ldisc.c:606
 tiocsetd drivers/tty/tty_io.c:2351 [inline]
 tty_ioctl+0x95b/0x1320 drivers/tty/tty_io.c:2595
 vfs_ioctl fs/ioctl.c:46 [inline]
 file_ioctl fs/ioctl.c:500 [inline]
 do_vfs_ioctl+0x7ae/0x1060 fs/ioctl.c:684
 SYSC_ioctl fs/ioctl.c:701 [inline]
 SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
 do_syscall_64+0x1e8/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

Freed by task 20807:
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 save_stack+0x45/0xd0 mm/kasan/kasan.c:447
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0x75/0xc0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xcc/0x270 mm/slab.c:3815
 kvfree+0x4d/0x60 mm/util.c:416
 seq_release fs/seq_file.c:368 [inline]
 single_release+0x7e/0xb0 fs/seq_file.c:605
 __fput+0x275/0x7a0 fs/file_table.c:210
 ____fput+0x16/0x20 fs/file_table.c:244
 task_work_run+0x114/0x190 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:191 [inline]
 exit_to_usermode_loop+0x1da/0x220 arch/x86/entry/common.c:164
 prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
 do_syscall_64+0x4bc/0x640 arch/x86/entry/common.c:297
 entry_SYSCALL_64_after_hwframe+0x42/0xb7

The buggy address belongs to the object at ffff88805ca52700
 which belongs to the cache kmalloc-4096 of size 4096
The buggy address is located 910 bytes to the right of
 4096-byte region [ffff88805ca52700, ffff88805ca53700)
The buggy address belongs to the page:
page:ffffea0001729480 count:1 mapcount:0 mapping:ffff88805ca52700 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffff88805ca52700 0000000000000000 0000000100000001
raw: ffffea0002251c20 ffffea000225f5a0 ffff8880aa800dc0 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88805ca53980: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805ca53a00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88805ca53a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                      ^
 ffff88805ca53b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88805ca53b80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================