A small CIFS buffer (448 bytes) isn't big enough to hold
SMB2_QUERY_INFO request along with user's input data from
CIFS_QUERY_INFO ioctl.  That is, if the user passed an input buffer >
344 bytes, the client will memcpy() off the end of @req->Buffer in
SMB2_query_info_init() thus causing the following KASAN splat:

  BUG: KASAN: slab-out-of-bounds in SMB2_query_info_init+0x242/0x250 [cifs]
  Write of size 1023 at addr ffff88801308c5a8 by task a.out/1240

  CPU: 1 PID: 1240 Comm: a.out Not tainted 6.7.0-rc4 #5
  Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS
  rel-1.16.2-3-gd478f380-rebuilt.opensuse.org 04/01/2014
  Call Trace:
   <TASK>
   dump_stack_lvl+0x4a/0x80
   print_report+0xcf/0x650
   ? srso_alias_return_thunk+0x5/0xfbef5
   ? srso_alias_return_thunk+0x5/0xfbef5
   ? srso_alias_return_thunk+0x5/0xfbef5
   ? __phys_addr+0x46/0x90
   kasan_report+0xd8/0x110
   ? SMB2_query_info_init+0x242/0x250 [cifs]
   ? SMB2_query_info_init+0x242/0x250 [cifs]
   kasan_check_range+0x105/0x1b0
   __asan_memcpy+0x3c/0x60
   SMB2_query_info_init+0x242/0x250 [cifs]
   ? __pfx_SMB2_query_info_init+0x10/0x10 [cifs]
   ? srso_alias_return_thunk+0x5/0xfbef5
   ? smb_rqst_len+0xa6/0xc0 [cifs]
   smb2_ioctl_query_info+0x4f4/0x9a0 [cifs]
   ? __pfx_smb2_ioctl_query_info+0x10/0x10 [cifs]
   ? __pfx_cifsConvertToUTF16+0x10/0x10 [cifs]
   ? kasan_set_track+0x25/0x30
   ? srso_alias_return_thunk+0x5/0xfbef5
   ? __kasan_kmalloc+0x8f/0xa0
   ? srso_alias_return_thunk+0x5/0xfbef5
   ? cifs_strndup_to_utf16+0x12d/0x1a0 [cifs]
   ? __build_path_from_dentry_optional_prefix+0x19d/0x2d0 [cifs]
   ? __pfx_smb2_ioctl_query_info+0x10/0x10 [cifs]
   cifs_ioctl+0x11c7/0x1de0 [cifs]
   ? __pfx_cifs_ioctl+0x10/0x10 [cifs]
   ? srso_alias_return_thunk+0x5/0xfbef5
   ? rcu_is_watching+0x23/0x50
   ? srso_alias_return_thunk+0x5/0xfbef5
   ? __rseq_handle_notify_resume+0x6cd/0x850
   ? __pfx___schedule+0x10/0x10
   ? blkcg_iostat_update+0x250/0x290
   ? srso_alias_return_thunk+0x5/0xfbef5
   ? ksys_write+0xe9/0x170
   __x64_sys_ioctl+0xc9/0x100
   do_syscall_64+0x47/0xf0
   entry_SYSCALL_64_after_hwframe+0x6f/0x77
  RIP: 0033:0x7f893dde49cf
  Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48
  89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <89>
  c2 3d 00 f0 ff ff 77 18 48 8b 44 24 18 64 48 2b 04 25 28 00 00
  RSP: 002b:00007ffc03ff4160 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
  RAX: ffffffffffffffda RBX: 00007ffc03ff4378 RCX: 00007f893dde49cf
  RDX: 00007ffc03ff41d0 RSI: 00000000c018cf07 RDI: 0000000000000003
  RBP: 00007ffc03ff4260 R08: 0000000000000410 R09: 0000000000000001
  R10: 00007f893dce7300 R11: 0000000000000246 R12: 0000000000000000
  R13: 00007ffc03ff4388 R14: 00007f893df15000 R15: 0000000000406de0
   </TASK>

Fix this by increasing size of SMB2_QUERY_INFO request buffers and
validating input length to prevent other callers from overflowing @req
in SMB2_query_info_init() as well.

Fixes: f5b05d62 ("cifs: add IOCTL for QUERY_INFO passthrough to userspace")
Cc: stable@vger.kernel.org
Reported-by: Robert Morris <rtm@csail.mit.edu>
Signed-off-by: Paulo Alcantara <pc@manguebit.com>
Signed-off-by: Steve French <stfrench@microsoft.com>