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BUG: KASAN: use-after-free in batadv_interface_tx+0xa45/0x14a0 net/batman-adv/soft-interface.c:227
Read of size 2 at addr ffff888091b3d04b by task syz-executor0/14481

CPU: 1 PID: 14481 Comm: syz-executor0 Not tainted 5.0.0-rc4+ #48
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+0x172/0x1f0 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+0xa45/0x14a0 net/batman-adv/soft-interface.c:227
 __netdev_start_xmit include/linux/netdevice.h:4385 [inline]
 netdev_start_xmit include/linux/netdevice.h:4394 [inline]
 dev_direct_xmit+0x346/0x640 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+0x3879/0x5ab0 net/packet/af_packet.c:2958
 sock_sendmsg_nosec net/socket.c:621 [inline]
 sock_sendmsg+0xdd/0x130 net/socket.c:631
 sock_write_iter+0x27c/0x3e0 net/socket.c:922
 call_write_iter include/linux/fs.h:1862 [inline]
 new_sync_write fs/read_write.c:474 [inline]
 __vfs_write+0x613/0x8e0 fs/read_write.c:487
 vfs_write+0x20c/0x580 fs/read_write.c:549
 ksys_write+0xea/0x1f0 fs/read_write.c:598
 __do_sys_write fs/read_write.c:610 [inline]
 __se_sys_write fs/read_write.c:607 [inline]
 __x64_sys_write+0x73/0xb0 fs/read_write.c:607
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x457e39
Code: ad b8 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 7b b8 fb ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007fd6efdccc78 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000457e39
RDX: 000000000000000e RSI: 0000000020000000 RDI: 0000000000000005
RBP: 000000000073bfa0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fd6efdcd6d4
R13: 00000000004c3b8d R14: 00000000004dc278 R15: 00000000ffffffff

Allocated by task 7831:
 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]
 __do_sys_unlink fs/namei.c:4109 [inline]
 __se_sys_unlink fs/namei.c:4107 [inline]
 __x64_sys_unlink+0x35/0x50 fs/namei.c:4107
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 7831:
 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
 do_unlinkat+0x146/0x6d0 fs/namei.c:4083
 __do_sys_unlink fs/namei.c:4109 [inline]
 __se_sys_unlink fs/namei.c:4107 [inline]
 __x64_sys_unlink+0x42/0x50 fs/namei.c:4107
 do_syscall_64+0x103/0x610 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff888091b3ce40
 which belongs to the cache names_cache of size 4096
The buggy address is located 523 bytes inside of
 4096-byte region [ffff888091b3ce40, ffff888091b3de40)
The buggy address belongs to the page:
page:ffffea000246cf00 count:1 mapcount:0 mapping:ffff88821bc45380 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea000295b908 ffffea00026da088 ffff88821bc45380
raw: 0000000000000000 ffff888091b3ce40 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888091b3cf00: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888091b3cf80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888091b3d000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                              ^
 ffff888091b3d080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff888091b3d100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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