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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 ffff888091b16c8b by task syz-executor0/12509

CPU: 0 PID: 12509 Comm: syz-executor0 Not tainted 5.0.0-rc2-next-20190117 #14
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+0x2754/0x6860 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
 __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
RSP: 002b:00007fc6150fcc78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000458099
RDX: 000000000000000e RSI: 0000000020000180 RDI: 0000000000000004
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc6150fd6d4
R13: 00000000004c568c R14: 00000000004d9358 R15: 00000000ffffffff

Allocated by task 12314:
 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+0x12d/0x710 mm/slab.c:3543
 getname_flags fs/namei.c:140 [inline]
 getname_flags+0xd6/0x5b0 fs/namei.c:129
 getname fs/namei.c:211 [inline]
 user_path_create fs/namei.c:3693 [inline]
 do_symlinkat+0xde/0x2c0 fs/namei.c:4146
 __do_sys_symlink fs/namei.c:4172 [inline]
 __se_sys_symlink fs/namei.c:4170 [inline]
 __x64_sys_symlink+0x59/0x80 fs/namei.c:4170
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 12314:
 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
 putname+0xef/0x130 fs/namei.c:261
 filename_create+0x29d/0x5a0 fs/namei.c:3658
 user_path_create fs/namei.c:3693 [inline]
 do_symlinkat+0xf3/0x2c0 fs/namei.c:4146
 __do_sys_symlink fs/namei.c:4172 [inline]
 __se_sys_symlink fs/namei.c:4170 [inline]
 __x64_sys_symlink+0x59/0x80 fs/namei.c:4170
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888091b16040
 which belongs to the cache names_cache of size 4096
The buggy address is located 3147 bytes inside of
 4096-byte region [ffff888091b16040, ffff888091b17040)
The buggy address belongs to the page:
page:ffffea000246c580 count:1 mapcount:0 mapping:ffff88821bc45380 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea000246c508 ffffea000157f708 ffff88821bc45380
raw: 0000000000000000 ffff888091b16040 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888091b16b80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888091b16c00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888091b16c80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff888091b16d00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888091b16d80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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