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BUG: KASAN: slab-out-of-bounds in decode_data.part.0+0x23b/0x270 drivers/net/hamradio/6pack.c:843
Write of size 1 at addr ffff888090fd94ce by task kworker/u4:4/255

CPU: 1 PID: 255 Comm: kworker/u4:4 Not tainted 5.9.0-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:77 [inline]
 dump_stack+0x1ac/0x21e lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xaf/0x499 mm/kasan/report.c:383
 __kasan_report mm/kasan/report.c:513 [inline]
 kasan_report.cold+0x20/0x37 mm/kasan/report.c:530
 __asan_report_store1_noabort+0x17/0x20 mm/kasan/generic_report.c:149
 decode_data.part.0+0x23b/0x270 drivers/net/hamradio/6pack.c:843
 decode_data drivers/net/hamradio/6pack.c:965 [inline]
 sixpack_decode drivers/net/hamradio/6pack.c:968 [inline]
 sixpack_receive_buf drivers/net/hamradio/6pack.c:458 [inline]
 sixpack_receive_buf+0xcfe/0x11fc drivers/net/hamradio/6pack.c:435
 tty_ldisc_receive_buf+0x15f/0x1c0 drivers/tty/tty_buffer.c:465
 tty_port_default_receive_buf+0x73/0xa0 drivers/tty/tty_port.c:38
 receive_buf drivers/tty/tty_buffer.c:481 [inline]
 flush_to_ldisc+0x210/0x380 drivers/tty/tty_buffer.c:533
 process_one_work+0x9ae/0x1770 kernel/workqueue.c:2269
 worker_thread+0x65f/0x1170 kernel/workqueue.c:2415
 kthread+0x3c6/0x4d0 kernel/kthread.c:292
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:294

Allocated by task 8269:
 kasan_save_stack+0x23/0x50 mm/kasan/common.c:48
 kasan_set_track mm/kasan/common.c:56 [inline]
 __kasan_kmalloc.constprop.0+0xcc/0xe0 mm/kasan/common.c:461
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:475
 __do_kmalloc_node mm/slab.c:3619 [inline]
 __kmalloc_node+0x4e/0x70 mm/slab.c:3626
 kmalloc_node include/linux/slab.h:577 [inline]
 kvmalloc_node+0x68/0x100 mm/util.c:574
 kvmalloc include/linux/mm.h:757 [inline]
 kvzalloc include/linux/mm.h:765 [inline]
 alloc_netdev_mqs+0x98/0xed0 net/core/dev.c:10330
 sixpack_open+0x104/0xac0 drivers/net/hamradio/6pack.c:563
 tty_ldisc_open+0xa3/0x110 drivers/tty/tty_ldisc.c:464
 tty_set_ldisc+0x310/0x6c0 drivers/tty/tty_ldisc.c:591
 tiocsetd drivers/tty/tty_io.c:2333 [inline]
 tty_ioctl+0xb2f/0x16a0 drivers/tty/tty_io.c:2593
 vfs_ioctl fs/ioctl.c:48 [inline]
 __do_sys_ioctl fs/ioctl.c:753 [inline]
 __se_sys_ioctl fs/ioctl.c:739 [inline]
 __x64_sys_ioctl+0x196/0x220 fs/ioctl.c:739
 do_syscall_64+0x32/0x80 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x44/0xa9

The buggy address belongs to the object at ffff888090fd8000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 1230 bytes to the right of
 4096-byte region [ffff888090fd8000, ffff888090fd9000)
The buggy address belongs to the page:
page:00000000ac579711 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x90fd8
head:00000000ac579711 order:1 compound_mapcount:0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea000228e608 ffffea0002600008 ffff8880aa440900
raw: 0000000000000000 ffff888090fd8000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888090fd9380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888090fd9400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff888090fd9480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                              ^
 ffff888090fd9500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888090fd9580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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