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BUG: KASAN: slab-out-of-bounds in batadv_interface_tx+0x1194/0x1880 net/batman-adv/soft-interface.c:226
Read of size 2 at addr ffff88809847dc8b by task syz-executor3/9443

CPU: 0 PID: 9443 Comm: syz-executor3 Not tainted 5.0.0-rc3 #36
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]
 __ia32_sys_sendto+0xdf/0x1a0 net/socket.c:1796
 do_syscall_32_irqs_on arch/x86/entry/common.c:326 [inline]
 do_fast_syscall_32+0x333/0xf98 arch/x86/entry/common.c:397
 entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
RIP: 0023:0xf7f3d869
Code: 85 d2 74 02 89 0a 5b 5d c3 8b 04 24 c3 8b 14 24 c3 8b 3c 24 c3 90 90 90 90 90 90 90 90 90 90 90 90 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 eb 0d 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 002b:00000000f5d390cc EFLAGS: 00000296 ORIG_RAX: 0000000000000171
RAX: ffffffffffffffda RBX: 0000000000000004 RCX: 0000000020000180
RDX: 000000000000000e RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 29074:
 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
 user_path_at_empty+0x2f/0x50 fs/namei.c:2608
 do_readlinkat+0x141/0x400 fs/stat.c:397
 __do_sys_readlink fs/stat.c:430 [inline]
 __se_sys_readlink fs/stat.c:427 [inline]
 __x64_sys_readlink+0x78/0xb0 fs/stat.c:427
 do_syscall_64+0x1a3/0x800 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 29074:
 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_lookup+0x359/0x530 fs/namei.c:2357
 user_path_at_empty+0x43/0x50 fs/namei.c:2608
 do_readlinkat+0x141/0x400 fs/stat.c:397
 __do_sys_readlink fs/stat.c:430 [inline]
 __se_sys_readlink fs/stat.c:427 [inline]
 __x64_sys_readlink+0x78/0xb0 fs/stat.c:427
 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 ffff88809847cc40
 which belongs to the cache names_cache of size 4096
The buggy address is located 75 bytes to the right of
 4096-byte region [ffff88809847cc40, ffff88809847dc40)
The buggy address belongs to the page:
page:ffffea0002611f00 count:1 mapcount:0 mapping:ffff88821bc45380 index:0x0 compound_mapcount: 0
flags: 0x1fffc0000010200(slab|head)
raw: 01fffc0000010200 ffffea000160dc88 ffffea0001666288 ffff88821bc45380
raw: 0000000000000000 ffff88809847cc40 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff88809847db80: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88809847dc00: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
>ffff88809847dc80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
                      ^
 ffff88809847dd00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff88809847dd80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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