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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 ffff88809f3f944e by task kworker/u4:8/586

CPU: 0 PID: 586 Comm: kworker/u4:8 Not tainted 5.6.0-rc3-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+0x197/0x210 lib/dump_stack.c:118
 print_address_description.constprop.0.cold+0xd4/0x30b mm/kasan/report.c:374
 __kasan_report.cold+0x1b/0x32 mm/kasan/report.c:506
 kasan_report+0x12/0x20 mm/kasan/common.c:641
 __asan_report_store1_noabort+0x17/0x20 mm/kasan/generic_report.c:137
 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+0xde4/0x1420 drivers/net/hamradio/6pack.c:435
 tty_ldisc_receive_buf+0x15f/0x1c0 drivers/tty/tty_buffer.c:465
 tty_port_default_receive_buf+0x7d/0xb0 drivers/tty/tty_port.c:38
 receive_buf drivers/tty/tty_buffer.c:481 [inline]
 flush_to_ldisc+0x222/0x390 drivers/tty/tty_buffer.c:533
 process_one_work+0xa05/0x17a0 kernel/workqueue.c:2264
 worker_thread+0x98/0xe40 kernel/workqueue.c:2410
 kthread+0x361/0x430 kernel/kthread.c:255
 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352

Allocated by task 9970:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 __kasan_kmalloc mm/kasan/common.c:515 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:488
 kasan_kmalloc+0x9/0x10 mm/kasan/common.c:529
 __do_kmalloc_node mm/slab.c:3616 [inline]
 __kmalloc_node+0x4e/0x70 mm/slab.c:3623
 kmalloc_node include/linux/slab.h:578 [inline]
 kvmalloc_node+0x68/0x100 mm/util.c:574
 kvmalloc include/linux/mm.h:645 [inline]
 kvzalloc include/linux/mm.h:653 [inline]
 alloc_netdev_mqs+0x98/0xe40 net/core/dev.c:9785
 sixpack_open+0x104/0xaaf drivers/net/hamradio/6pack.c:563
 tty_ldisc_open.isra.0+0xa3/0x110 drivers/tty/tty_ldisc.c:464
 tty_set_ldisc+0x30e/0x6b0 drivers/tty/tty_ldisc.c:591
 tiocsetd drivers/tty/tty_io.c:2337 [inline]
 tty_ioctl+0xe8d/0x14f0 drivers/tty/tty_io.c:2597
 vfs_ioctl fs/ioctl.c:47 [inline]
 ksys_ioctl+0x123/0x180 fs/ioctl.c:763
 __do_sys_ioctl fs/ioctl.c:772 [inline]
 __se_sys_ioctl fs/ioctl.c:770 [inline]
 __x64_sys_ioctl+0x73/0xb0 fs/ioctl.c:770
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9713:
 save_stack+0x23/0x90 mm/kasan/common.c:72
 set_track mm/kasan/common.c:80 [inline]
 kasan_set_free_info mm/kasan/common.c:337 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:476
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:485
 __cache_free mm/slab.c:3426 [inline]
 kfree+0x10a/0x2c0 mm/slab.c:3757
 tomoyo_realpath_from_path+0x1a7/0x660 security/tomoyo/realpath.c:289
 tomoyo_init_log+0xc5a/0x2070 security/tomoyo/audit.c:263
 tomoyo_supervisor+0x32c/0xee0 security/tomoyo/common.c:2097
 tomoyo_audit_env_log security/tomoyo/environ.c:36 [inline]
 tomoyo_env_perm+0x18e/0x210 security/tomoyo/environ.c:63
 tomoyo_environ security/tomoyo/domain.c:674 [inline]
 tomoyo_find_next_domain+0x1354/0x1f6c security/tomoyo/domain.c:881
 tomoyo_bprm_check_security security/tomoyo/tomoyo.c:107 [inline]
 tomoyo_bprm_check_security+0x124/0x1a0 security/tomoyo/tomoyo.c:97
 security_bprm_check+0x63/0xb0 security/security.c:816
 search_binary_handler+0x71/0x570 fs/exec.c:1649
 exec_binprm fs/exec.c:1705 [inline]
 __do_execve_file.isra.0+0x12fc/0x2270 fs/exec.c:1825
 do_execveat_common fs/exec.c:1871 [inline]
 do_execve fs/exec.c:1888 [inline]
 __do_sys_execve fs/exec.c:1964 [inline]
 __se_sys_execve fs/exec.c:1959 [inline]
 __x64_sys_execve+0x8f/0xc0 fs/exec.c:1959
 do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff88809f3f8000
 which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 1102 bytes to the right of
 4096-byte region [ffff88809f3f8000, ffff88809f3f9000)
The buggy address belongs to the page:
page:ffffea00027cfe00 refcount:1 mapcount:0 mapping:ffff8880aa402000 index:0x0 compound_mapcount: 0
flags: 0xfffe0000010200(slab|head)
raw: 00fffe0000010200 ffffea0002266188 ffffea00027f3708 ffff8880aa402000
raw: 0000000000000000 ffff88809f3f8000 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809f3f9300: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809f3f9380: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
>ffff88809f3f9400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                                              ^
 ffff88809f3f9480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809f3f9500: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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