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BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:372 [inline]
BUG: KASAN: slab-out-of-bounds in pdu_read+0x94/0x100 net/9p/protocol.c:64
Read of size 33088 at addr ffff888088dc972d by task syz-executor.3/23777

CPU: 0 PID: 23777 Comm: syz-executor.3 Not tainted 4.14.193-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:17 [inline]
 dump_stack+0x1b2/0x283 lib/dump_stack.c:58
 print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
 kasan_report_error.cold+0x8a/0x194 mm/kasan/report.c:351
 kasan_report+0x6f/0x7b mm/kasan/report.c:409
 memcpy+0x20/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:372 [inline]
 pdu_read+0x94/0x100 net/9p/protocol.c:64
 p9pdu_vreadf net/9p/protocol.c:167 [inline]
 p9pdu_readf+0x381/0x1970 net/9p/protocol.c:540
 p9_client_version net/9p/client.c:990 [inline]
 p9_client_create+0x9b2/0x12c0 net/9p/client.c:1088
 v9fs_session_init+0x1c5/0x1540 fs/9p/v9fs.c:422
 v9fs_mount+0x73/0x860 fs/9p/vfs_super.c:135
 mount_fs+0x92/0x2a0 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2549 [inline]
 do_mount+0xe53/0x2a00 fs/namespace.c:2879
 SYSC_mount fs/namespace.c:3095 [inline]
 SyS_mount+0xa8/0x120 fs/namespace.c:3072
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x45d4d9
RSP: 002b:00007f4837706c78 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0000000000021180 RCX: 000000000045d4d9
RDX: 0000000020000100 RSI: 0000000020000040 RDI: 0000000000000000
RBP: 000000000118d030 R08: 0000000020000200 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cfec
R13: 00007ffe6868d7df R14: 00007f48377079c0 R15: 000000000118cfec

Allocated by task 23777:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
 __do_kmalloc mm/slab.c:3720 [inline]
 __kmalloc+0x15a/0x400 mm/slab.c:3729
 kmalloc include/linux/slab.h:493 [inline]
 p9_fcall_alloc+0x19/0x90 net/9p/client.c:242
 p9_tag_alloc net/9p/client.c:312 [inline]
 p9_client_prepare_req.part.0+0x7f8/0xb60 net/9p/client.c:728
 p9_client_prepare_req net/9p/client.c:718 [inline]
 p9_client_rpc+0x170/0x1520 net/9p/client.c:763
 p9_client_version net/9p/client.c:980 [inline]
 p9_client_create+0x92f/0x12c0 net/9p/client.c:1088
 v9fs_session_init+0x1c5/0x1540 fs/9p/v9fs.c:422
 v9fs_mount+0x73/0x860 fs/9p/vfs_super.c:135
 mount_fs+0x92/0x2a0 fs/super.c:1237
 vfs_kern_mount.part.0+0x5b/0x470 fs/namespace.c:1046
 vfs_kern_mount fs/namespace.c:1036 [inline]
 do_new_mount fs/namespace.c:2549 [inline]
 do_mount+0xe53/0x2a00 fs/namespace.c:2879
 SYSC_mount fs/namespace.c:3095 [inline]
 SyS_mount+0xa8/0x120 fs/namespace.c:3072
 do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
 entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 23068:
 save_stack mm/kasan/kasan.c:447 [inline]
 set_track mm/kasan/kasan.c:459 [inline]
 kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
 __cache_free mm/slab.c:3496 [inline]
 kfree+0xc9/0x250 mm/slab.c:3815
 skb_free_head net/core/skbuff.c:554 [inline]
 pskb_expand_head+0x895/0xd30 net/core/skbuff.c:1495
 __skb_cow include/linux/skbuff.h:2936 [inline]
 skb_cow_head include/linux/skbuff.h:2970 [inline]
 __vlan_insert_inner_tag include/linux/if_vlan.h:320 [inline]
 __vlan_insert_tag include/linux/if_vlan.h:365 [inline]
 skb_vlan_push+0x556/0x6e0 net/core/skbuff.c:5182
 ____bpf_skb_vlan_push net/core/filter.c:1971 [inline]
 bpf_skb_vlan_push+0x8f/0x4f0 net/core/filter.c:1961
 0xffffffffa00c0f24

The buggy address belongs to the object at ffff888088dc9700
 which belongs to the cache kmalloc-16384 of size 16384
The buggy address is located 45 bytes inside of
 16384-byte region [ffff888088dc9700, ffff888088dcd700)
The buggy address belongs to the page:
page:ffffea0002237200 count:1 mapcount:0 mapping:ffff888088dc9700 index:0x0 compound_mapcount: 0
flags: 0xfffe0000008100(slab|head)
raw: 00fffe0000008100 ffff888088dc9700 0000000000000000 0000000100000001
raw: ffffea00014fe620 ffffea0000ce1420 ffff88812fe51200 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff888088dcb600: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff888088dcb680: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff888088dcb700: 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc fc
                               ^
 ffff888088dcb780: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff888088dcb800: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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