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BUG: KASAN: use-after-free in memcmp+0x127/0x150 lib/string.c:861
Read of size 1 at addr ffff8801bb8bb531 by task syz-executor400/4735

CPU: 0 PID: 4735 Comm: syz-executor400 Not tainted 4.19.0-rc2-next-20180904+ #55
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
 __asan_report_load1_noabort+0x14/0x20 mm/kasan/report.c:430
 memcmp+0x127/0x150 lib/string.c:861
 memcmp include/linux/string.h:386 [inline]
 rhashtable_compare include/linux/rhashtable.h:462 [inline]
 __rhashtable_lookup.isra.8.constprop.19+0x70f/0xd50 include/linux/rhashtable.h:484
 rhashtable_lookup include/linux/rhashtable.h:516 [inline]
 rhashtable_lookup_fast include/linux/rhashtable.h:542 [inline]
 rds_add_bound net/rds/bind.c:117 [inline]
 rds_bind+0x7c9/0x1510 net/rds/bind.c:238
 __sys_bind+0x331/0x440 net/socket.c:1482
 __do_sys_bind net/socket.c:1493 [inline]
 __se_sys_bind net/socket.c:1491 [inline]
 __x64_sys_bind+0x73/0xb0 net/socket.c:1491
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe
RIP: 0033:0x4411d9
Code: e8 6c e8 ff ff 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 cb 09 fc ff c3 66 2e 0f 1f 84 00 00 00 00
RSP: 002b:00007ffc9c4d33d8 EFLAGS: 00000217 ORIG_RAX: 0000000000000031
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00000000004411d9
RDX: 0000000000000010 RSI: 00000000200002c0 RDI: 0000000000000004
RBP: 0000000000054aa8 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000217 R12: 0000000000000000
R13: 00000000004020c0 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 4733:
 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
 kasan_slab_alloc+0x12/0x20 mm/kasan/kasan.c:490
 kmem_cache_alloc+0x12e/0x710 mm/slab.c:3554
 sk_prot_alloc+0x69/0x2e0 net/core/sock.c:1462
 sk_alloc+0x106/0x17b0 net/core/sock.c:1522
 rds_create+0x14f/0x770 net/rds/af_rds.c:666
 __sock_create+0x53c/0x940 net/socket.c:1276
 sock_create net/socket.c:1316 [inline]
 __sys_socket+0x106/0x260 net/socket.c:1346
 __do_sys_socket net/socket.c:1355 [inline]
 __se_sys_socket net/socket.c:1353 [inline]
 __x64_sys_socket+0x73/0xb0 net/socket.c:1353
 do_syscall_64+0x1b9/0x820 arch/x86/entry/common.c:290
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

Freed by task 4733:
 save_stack+0x43/0xd0 mm/kasan/kasan.c:448
 set_track mm/kasan/kasan.c:460 [inline]
 __kasan_slab_free+0x11a/0x170 mm/kasan/kasan.c:521
 kasan_slab_free+0xe/0x10 mm/kasan/kasan.c:528
 __cache_free mm/slab.c:3498 [inline]
 kmem_cache_free+0x86/0x280 mm/slab.c:3756
 sk_prot_free net/core/sock.c:1503 [inline]
 __sk_destruct+0x70a/0xa60 net/core/sock.c:1587
 sk_destruct+0x78/0x90 net/core/sock.c:1595
 __sk_free+0xcf/0x300 net/core/sock.c:1606
 sk_free+0x42/0x50 net/core/sock.c:1617
 sock_put include/net/sock.h:1691 [inline]
 rds_release+0x3e9/0x570 net/rds/af_rds.c:91
 __sock_release+0xd7/0x250 net/socket.c:580
 sock_close+0x19/0x20 net/socket.c:1140
 __fput+0x3c1/0xa80 fs/file_table.c:279
 ____fput+0x15/0x20 fs/file_table.c:312
 task_work_run+0x1e8/0x2a0 kernel/task_work.c:113
 tracehook_notify_resume include/linux/tracehook.h:193 [inline]
 exit_to_usermode_loop+0x318/0x380 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+0x6be/0x820 arch/x86/entry/common.c:293
 entry_SYSCALL_64_after_hwframe+0x49/0xbe

The buggy address belongs to the object at ffff8801bb8bb0c0
 which belongs to the cache RDS of size 1608
The buggy address is located 1137 bytes inside of
 1608-byte region [ffff8801bb8bb0c0, ffff8801bb8bb708)
The buggy address belongs to the page:
page:ffffea0006ee2ec0 count:1 mapcount:0 mapping:ffff8801cdc8ce40 index:0x0
flags: 0x2fffc0000000100(slab)
raw: 02fffc0000000100 ffffea00070c4688 ffffea0006ec0b48 ffff8801cdc8ce40
raw: 0000000000000000 ffff8801bb8bb0c0 0000000100000002 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
 ffff8801bb8bb400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801bb8bb480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff8801bb8bb500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                                     ^
 ffff8801bb8bb580: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff8801bb8bb600: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
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