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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 ffff8880a0656a8b by task syz-executor0/21177

CPU: 1 PID: 21177 Comm: syz-executor0 Not tainted 5.0.0-rc3+ #31
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:2933 [inline]
 packet_sendmsg+0x27fb/0x6920 net/packet/af_packet.c:2958
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg+0xdd/0x130 net/socket.c:631
 __sys_sendto+0x387/0x5f0 net/socket.c:1788
 __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: 0033:0x458099
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
netlink: 'syz-executor1': attribute type 1 has an invalid length.
RSP: 002b:00007ff8346e3c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000458099
RDX: 0000000000000012 RSI: 00000000200001c0 RDI: 0000000000000003
RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ff8346e46d4
R13: 00000000004c568c R14: 00000000004d9358 R15: 00000000ffffffff

Allocated by task 7644:
 save_stack+0x45/0xd0 mm/kasan/common.c:73
 set_track mm/kasan/common.c:85 [inline]
 __kasan_kmalloc mm/kasan/common.c:496 [inline]
 __kasan_kmalloc.constprop.0+0xcf/0xe0 mm/kasan/common.c:469
 kasan_kmalloc mm/kasan/common.c:504 [inline]
 kasan_slab_alloc+0xf/0x20 mm/kasan/common.c:411
 kmem_cache_alloc_node+0x144/0x710 mm/slab.c:3633
 alloc_task_struct_node kernel/fork.c:158 [inline]
 dup_task_struct kernel/fork.c:845 [inline]
 copy_process+0x405b/0x8710 kernel/fork.c:1753
 _do_fork+0x1a9/0x1170 kernel/fork.c:2227
 __do_sys_clone kernel/fork.c:2334 [inline]
 __se_sys_clone kernel/fork.c:2328 [inline]
 __x64_sys_clone+0xbf/0x150 kernel/fork.c:2328
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 16:
 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:458
 kasan_slab_free+0xe/0x10 mm/kasan/common.c:466
 __cache_free mm/slab.c:3487 [inline]
 kmem_cache_free+0x86/0x260 mm/slab.c:3749
 free_task_struct kernel/fork.c:163 [inline]
 free_task+0x170/0x1f0 kernel/fork.c:458
 __put_task_struct+0x2e0/0x630 kernel/fork.c:731
 put_task_struct include/linux/sched/task.h:98 [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

The buggy address belongs to the object at ffff8880a06564c0
 which belongs to the cache task_struct(102:syz4) of size 6080
The buggy address is located 1483 bytes inside of
 6080-byte region [ffff8880a06564c0, ffff8880a0657c80)
The buggy address belongs to the page:
page:ffffea0002819580 count:1 mapcount:0 mapping:ffff888099e41300 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea0001977788 ffffea0001acba08 ffff888099e41300
raw: 0000000000000000 ffff8880a06564c0 0000000100000001 ffff88806938eec0
page dumped because: kasan: bad access detected
page->mem_cgroup:ffff88806938eec0

Memory state around the buggy address:
 ffff8880a0656980: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a0656a00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8880a0656a80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff8880a0656b00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880a0656b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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