CIFS: No dialect specified on mount. Default has changed to a more secure dialect, SMB2.1 or later (e.g. SMB3.1.1), from CIFS (SMB1). To use the less secure SMB1 dialect to access old servers which do not support SMB3.1.1 (or even SMB3 or SMB2.1) specify vers=1.0 on mount.
CIFS: Attempting to mount //127.0.0.1/share
CIFS: VFS: \\127.0.0.1 Error -512 sending data on socket to server
------------[ cut here ]------------
server->in_flight == 0
WARNING: fs/smb/client/smb2ops.c:104 at smb2_add_credits+0x1249/0x2b70 fs/smb/client/smb2ops.c:104, CPU#0: syz.0.0/5329
Modules linked in:
CPU: 0 UID: 0 PID: 5329 Comm: syz.0.0 Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:smb2_add_credits+0x1249/0x2b70 fs/smb/client/smb2ops.c:104
Code: de 83 e6 01 31 ff e8 86 8b bc fe f6 c3 01 75 0a e8 3c 87 bc fe e9 22 13 00 00 0f 1f 44 00 00 e8 2d 87 bc fe e9 13 13 00 00 90 <0f> 0b 90 80 3d bc a2 36 0d 01 0f 85 9e 03 00 00 e8 12 87 bc fe 49
RSP: 0018:ffffc9000e0e7238 EFLAGS: 00010246
RAX: ffffffff830a8fa8 RBX: 1ffff110024e0c61 RCX: 0000000000000002
RDX: ffff88803be02540 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000200 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: ffffffff830abd00 R12: ffff888012706308
R13: ffffc9000e0e7450 R14: ffff888012706000 R15: 0000000000000000
FS:  00007f154b3c36c0(0000) GS:ffff88808c53f000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f154b3e49a0 CR3: 00000000129ad000 CR4: 0000000000352ef0
Call Trace:
 <TASK>
 add_credits fs/smb/client/cifsglob.h:894 [inline]
 compound_send_recv+0x13b4/0x2b90 fs/smb/client/transport.c:979
 cifs_send_recv+0x42/0x60 fs/smb/client/transport.c:1106
 SMB2_negotiate+0x164d/0x4030 fs/smb/client/smb2pdu.c:1188
 cifs_negotiate_protocol+0x45d/0x680 fs/smb/client/connect.c:4043
 cifs_get_smb_ses+0x1104/0x1ff0 fs/smb/client/connect.c:2492
 cifs_mount_get_session+0xf1/0x450 fs/smb/client/connect.c:3578
 get_session fs/smb/client/dfs.c:65 [inline]
 dfs_mount_share+0x22e/0x990 fs/smb/client/dfs.c:275
 cifs_mount+0xcc/0xbf0 fs/smb/client/connect.c:3860
 cifs_smb3_do_mount+0x2d0/0x8a0 fs/smb/client/cifsfs.c:1024
 smb3_get_tree_common fs/smb/client/fs_context.c:897 [inline]
 smb3_get_tree+0x2dd/0x400 fs/smb/client/fs_context.c:917
 vfs_get_tree+0x92/0x2a0 fs/super.c:1700
 fc_mount fs/namespace.c:1198 [inline]
 do_new_mount_fc fs/namespace.c:3765 [inline]
 do_new_mount+0x319/0xdc0 fs/namespace.c:3841
 do_mount fs/namespace.c:4174 [inline]
 __do_sys_mount fs/namespace.c:4390 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4367
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x174/0x580 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f154a59e019
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 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 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f154b3c2fe8 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f154a826090 RCX: 00007f154a59e019
RDX: 0000200000000400 RSI: 0000200000000300 RDI: 0000200000000200
RBP: 00007f154a63500c R08: 0000200000000500 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f154a826128 R14: 00007f154a826090 R15: 00007ffda3753e18
 </TASK>