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BUG: KASAN: slab-out-of-bounds in memcpy include/linux/string.h:345 [inline]
BUG: KASAN: slab-out-of-bounds in pdu_read+0x90/0xd0 net/9p/protocol.c:59
Read of size 19388 at addr ffff8801af86aa6d by task syz-executor744/4699

CPU: 0 PID: 4699 Comm: syz-executor744 Not tainted 4.18.0-rc5-next-20180720+ #12
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+0x1c9/0x2b4 lib/dump_stack.c:113
 print_address_description+0x6c/0x20b mm/kasan/report.c:256
 kasan_report_error mm/kasan/report.c:354 [inline]
 kasan_report.cold.7+0x242/0x30d mm/kasan/report.c:412
 check_memory_region_inline mm/kasan/kasan.c:260 [inline]
 check_memory_region+0x13e/0x1b0 mm/kasan/kasan.c:267
 memcpy+0x23/0x50 mm/kasan/kasan.c:302
 memcpy include/linux/string.h:345 [inline]
 pdu_read+0x90/0xd0 net/9p/protocol.c:59
 p9pdu_vreadf net/9p/protocol.c:162 [inline]
 p9pdu_readf+0x579/0x2170 net/9p/protocol.c:536
 p9_client_version net/9p/client.c:900 [inline]
 p9_client_create+0x6d0/0x1537 net/9p/client.c:974
 v9fs_session_init+0x21a/0x1a80 fs/9p/v9fs.c:400
 v9fs_mount+0x7c/0x900 fs/9p/vfs_super.c:135
 legacy_get_tree+0x131/0x460 fs/fs_context.c:674
 vfs_get_tree+0x1cb/0x5c0 fs/super.c:1743
 do_new_mount fs/namespace.c:2603 [inline]
 do_mount+0x6f2/0x1e20 fs/namespace.c:2927
 ksys_mount+0x12d/0x140 fs/namespace.c:3143
 __do_sys_mount fs/namespace.c:3157 [inline]
 __se_sys_mount fs/namespace.c:3154 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3154
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x446039
Code: e8 dc bb 02 00 48 83 c4 18 c3 0f 1f 80 00 00 00 00 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 ab 0e fc ff c3 66 2e 0f 1f 84 00 00 00 00 
RSP: 002b:00007ff6f8a3bce8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00000000006dbc24 RCX: 0000000000446039
RDX: 0000000020000040 RSI: 0000000020000000 RDI: 0000000000000000
RBP: 00000000006dbc20 R08: 00000000200001c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffd570b3d4f R14: 00007ff6f8a3c9c0 R15: 0000000000000001

Allocated by task 4699:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 kasan_kmalloc+0xc4/0xe0 mm/kasan/kasan.c:553
 __do_kmalloc mm/slab.c:3718 [inline]
 __kmalloc+0x14e/0x760 mm/slab.c:3727
 kmalloc include/linux/slab.h:518 [inline]
 p9_fcall_alloc+0x1e/0x90 net/9p/client.c:237
 p9_tag_alloc net/9p/client.c:267 [inline]
 p9_client_prepare_req.part.8+0x132/0xa00 net/9p/client.c:640
 p9_client_prepare_req net/9p/client.c:675 [inline]
 p9_client_rpc+0x242/0x1330 net/9p/client.c:675
 p9_client_version net/9p/client.c:890 [inline]
 p9_client_create+0xca4/0x1537 net/9p/client.c:974
 v9fs_session_init+0x21a/0x1a80 fs/9p/v9fs.c:400
 v9fs_mount+0x7c/0x900 fs/9p/vfs_super.c:135
 legacy_get_tree+0x131/0x460 fs/fs_context.c:674
 vfs_get_tree+0x1cb/0x5c0 fs/super.c:1743
 do_new_mount fs/namespace.c:2603 [inline]
 do_mount+0x6f2/0x1e20 fs/namespace.c:2927
 ksys_mount+0x12d/0x140 fs/namespace.c:3143
 __do_sys_mount fs/namespace.c:3157 [inline]
 __se_sys_mount fs/namespace.c:3154 [inline]
 __x64_sys_mount+0xbe/0x150 fs/namespace.c:3154
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 0:
(stack is not available)

The buggy address belongs to the object at ffff8801af86aa40
 which belongs to the cache kmalloc-16384 of size 16384
The buggy address is located 45 bytes inside of
 16384-byte region [ffff8801af86aa40, ffff8801af86ea40)
The buggy address belongs to the page:
page:ffffea0006be1a00 count:1 mapcount:0 mapping:ffff8801da802200 index:0x0 compound_mapcount: 0
flags: 0x2fffc0000010200(slab|head)
raw: 02fffc0000010200 ffffea0006be6008 ffff8801da801c48 ffff8801da802200
raw: 0000000000000000 ffff8801af86aa40 0000000100000001 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801af86c900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff8801af86c980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff8801af86ca00: 00 00 00 00 00 00 00 00 00 00 00 00 fc fc fc fc
                                                       ^
 ffff8801af86ca80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
 ffff8801af86cb00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
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