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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 ffff8880941f630b by task syz-executor1/17251

CPU: 0 PID: 17251 Comm: syz-executor1 Not tainted 5.0.0-rc4+ #52
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
audit: type=1804 audit(1548849426.591:112): pid=17261 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=invalid_pcr cause=open_writers comm="syz-executor2" name="/root/syzkaller-testdir886638483/syzkaller.CpIGFp/1545/memory.events" dev="sda1" ino=16536 res=1
 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: 0033:0x458089
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:00007f69ffe77c78 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 0000000000458089
RDX: 000000000000000e RSI: 0000000020000180 RDI: 0000000000000003
RBP: 000000000073bf00 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f69ffe786d4
R13: 00000000004c56f0 R14: 00000000004d94c0 R15: 00000000ffffffff

Allocated by task 23131:
 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+0x9/0x10 mm/kasan/common.c:504
 kmem_cache_alloc_trace+0x151/0x760 mm/slab.c:3609
 kmalloc include/linux/slab.h:545 [inline]
 kzalloc include/linux/slab.h:740 [inline]
 kernfs_fop_open+0x342/0x1030 fs/kernfs/file.c:648
 do_dentry_open+0x48a/0x1210 fs/open.c:771
 vfs_open+0xa0/0xd0 fs/open.c:880
 do_last fs/namei.c:3418 [inline]
 path_openat+0x144f/0x5650 fs/namei.c:3534
 do_filp_open+0x26f/0x370 fs/namei.c:3564
 do_sys_open+0x59a/0x7c0 fs/open.c:1063
 __do_sys_open fs/open.c:1081 [inline]
 __se_sys_open fs/open.c:1076 [inline]
 __x64_sys_open+0x7e/0xc0 fs/open.c:1076
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 23131:
 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]
 kfree+0xcf/0x230 mm/slab.c:3806
 kernfs_fop_release+0x129/0x1a0 fs/kernfs/file.c:783
 __fput+0x3c5/0xb10 fs/file_table.c:278
 ____fput+0x16/0x20 fs/file_table.c:309
 task_work_run+0x1f4/0x2b0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:188 [inline]
 exit_to_usermode_loop+0x32a/0x3b0 arch/x86/entry/common.c:166
 prepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
 syscall_return_slowpath arch/x86/entry/common.c:268 [inline]
 do_syscall_64+0x696/0x800 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8880941f62c0
 which belongs to the cache kmalloc-512 of size 512
The buggy address is located 75 bytes inside of
 512-byte region [ffff8880941f62c0, ffff8880941f64c0)
The buggy address belongs to the page:
page:ffffea0002507d80 count:1 mapcount:0 mapping:ffff88812c3f0940 index:0x0
flags: 0x1fffc0000000200(slab)
raw: 01fffc0000000200 ffffea000184ff48 ffffea00027f4448 ffff88812c3f0940
kobject: 'loop5' (00000000bea3bf9f): fill_kobj_path: path = '/devices/virtual/block/loop5'
raw: 0000000000000000 ffff8880941f6040 0000000100000006 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8880941f6200: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
 ffff8880941f6280: fc fc fc fc fc fc fc fc fb fb fb fb fb fb fb fb
>ffff8880941f6300: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                      ^
 ffff8880941f6380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8880941f6400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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