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BUG: KASAN: use-after-free in batadv_interface_tx+0x1194/0x1880 net/batman-adv/soft-interface.c:226
Read of size 2 at addr ffff88809739384b by task syz-executor5/31624

CPU: 0 PID: 31624 Comm: syz-executor5 Not tainted 4.20.0+ #8
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+0x1db/0x2d0 lib/dump_stack.c:113
 print_address_description.cold+0x7c/0x20d mm/kasan/report.c:187
 kasan_report.cold+0x1b/0x40 mm/kasan/report.c:317
 __asan_report_load_n_noabort+0xf/0x20 mm/kasan/generic_report.c:145
 batadv_interface_tx+0x1194/0x1880 net/batman-adv/soft-interface.c:226
 __netdev_start_xmit include/linux/netdevice.h:4382 [inline]
 netdev_start_xmit include/linux/netdevice.h:4391 [inline]
 dev_direct_xmit+0x368/0x670 net/core/dev.c:3930
 packet_direct_xmit+0xfb/0x170 net/packet/af_packet.c:246
 packet_snd net/packet/af_packet.c:2932 [inline]
 packet_sendmsg+0x2753/0x6830 net/packet/af_packet.c:2957
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg+0xdd/0x130 net/socket.c:631
 __sys_sendto+0x387/0x5f0 net/socket.c:1788
TCP: request_sock_TCPv6: Possible SYN flooding on port 20002. Sending cookies.  Check SNMP counters.
 __do_sys_sendto net/socket.c:1800 [inline]
 __se_sys_sendto net/socket.c:1796 [inline]
 __x64_sys_sendto+0xe1/0x1a0 net/socket.c:1796
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457ec9
Code: 6d b7 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 3b b7 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fa8f601cc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000457ec9
RDX: 000000000000004c RSI: 0000000020000180 RDI: 000000000000000a
RBP: 000000000073c040 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fa8f601d6d4
R13: 00000000004c5284 R14: 00000000004d8ba8 R15: 00000000ffffffff

Allocated by task 29146:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 kasan_kmalloc mm/kasan/common.c:482 [inline]
 kasan_kmalloc+0xcf/0xe0 mm/kasan/common.c:455
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:397
 kmem_cache_alloc+0x12d/0x710 mm/slab.c:3541
 kmem_cache_zalloc include/linux/slab.h:730 [inline]
 __delayacct_tsk_init+0x20/0x80 kernel/delayacct.c:45
 delayacct_tsk_init include/linux/delayacct.h:112 [inline]
 copy_process+0x410d/0x8730 kernel/fork.c:1803
 _do_fork+0x1a9/0x1170 kernel/fork.c:2222
 __do_sys_clone kernel/fork.c:2329 [inline]
 __se_sys_clone kernel/fork.c:2323 [inline]
 __x64_sys_clone+0xbf/0x150 kernel/fork.c:2323
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 9:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 __kasan_slab_free+0x102/0x150 mm/kasan/common.c:444
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:452
 __cache_free mm/slab.c:3485 [inline]
 kmem_cache_free+0x86/0x260 mm/slab.c:3747
 delayacct_tsk_free include/linux/delayacct.h:121 [inline]
 __put_task_struct+0x1f4/0x630 kernel/fork.c:731
IPVS: set_ctl: invalid protocol: 44 172.20.20.187:20002
 put_task_struct include/linux/sched/task.h:96 [inline]
 delayed_put_task_struct+0x2fd/0x4d0 kernel/exit.c:181
 __rcu_reclaim kernel/rcu/rcu.h:240 [inline]
 rcu_do_batch kernel/rcu/tree.c:2452 [inline]
 invoke_rcu_callbacks kernel/rcu/tree.c:2773 [inline]
 rcu_process_callbacks+0xc4a/0x1680 kernel/rcu/tree.c:2754
 __do_softirq+0x30b/0xb11 kernel/softirq.c:292
IPVS: length: 27 != 24

The buggy address belongs to the object at ffff8880973937d0
 which belongs to the cache task_delay_info(60:syz1) of size 136
The buggy address is located 123 bytes inside of
 136-byte region [ffff8880973937d0, ffff888097393858)
The buggy address belongs to the page:
page:ffffea00025ce4c0 count:1 mapcount:0 mapping:ffff88808f049500 index:0xffff888097393898
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea0002166cc8 ffffea00022b9a48 ffff88808f049500
raw: ffff888097393898 ffff888097393000 0000000100000012 ffff888069432980
page dumped because: kasan: bad access detected
IPVS: set_ctl: invalid protocol: 44 172.20.20.187:20002
page->mem_cgroup:ffff888069432980

Memory state around the buggy address:
 ffff888097393700: fc fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888097393780: fb fb fc fc fc fc fc fc fc fc fb fb fb fb fb fb
>ffff888097393800: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc
                                              ^
 ffff888097393880: fc fc fc fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888097393900: fb fb fb fb fc fc fc fc fc fc fc fc 00 00 00 00
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