compiling with W=2 pointed out that "written may be used uninitialized"

Fixes: 20d72b00ca81 ("netfs: Fix the request's work item to not require a ref")
Cc: stable@vger.kernel.org
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs_copy_folioq_to_iter() copies a requested number of bytes from
a folio queue into the destination iterator.  Since the encrypted
SMB2 READ path was changed to pass the server-declared payload
length (data_len) instead of the larger folioq buffer length, the
caller can ask for fewer bytes than the folio queue holds.

In that case the helper continues walking the remaining folios after
data_size has reached zero and calls copy_folio_to_iter() with
len = 0, which is unnecessary work.

The helper also returns 0 (success) when the folio queue is
exhausted before data_size bytes have been copied.  The caller has
no way to distinguish that from a full copy and the reported
transfer count ends up larger than the amount of data placed in the
iterator.

Add an early exit when data_size reaches zero, and return an error
when the folio queue is exhausted before all requested bytes have
been copied.

Signed-off-by: Jeremy Erazo <mendozayt13@gmail.com>
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

Pull smb client fixes from Steve French:
 - Fix missing lock
 - Fix dentry in use after unmounting
 - cifs.upcall security fix
 - require CAP_NET_ADMIN for swn netlink
 - change allocation in DUP_CTX_STR to GFP_KERNEL
 - minor smbdirect debug fix
 - handle_read_data() folio fix

* tag 'v7.1-rc5-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  smb: client: change allocation requirements in DUP_CTX_STR macro
  smb: client: require net admin for CIFS SWN netlink
  smb: smbdirect: divide, not multiply, milliseconds by 1000
  cifs: Fix busy dentry used after unmounting
  smb: client: use data_len for SMB2 READ encrypted folioq copy
  smb: client: reject userspace cifs.spnego descriptions
  smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked()

Currently, the macro DUP_CTX_STR allocates new_ctx->field using
GFP_ATOMIC. DUP_CTX_STR is only used in smb3_fs_context_dup(), which
is never called in an atomic context. Using GFP_ATOMIC puts unnecessary
pressure on emergency memory pools.

Change GFP_ATOMIC to GFP_KERNEL.

Signed-off-by: Fredric Cover <fredric.cover.lkernel@gmail.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

CIFS_GENL_CMD_SWN_NOTIFY is the userspace witness-notify command.  The
intended sender is the cifs.witness helper, but the generic-netlink
operation currently has no capability flag, so any local process can send
RESOURCE_CHANGE or CLIENT_MOVE notifications to the in-kernel witness
handler.

The same family exposes CIFS_GENL_MCGRP_SWN without multicast-group
capability flags.  Register messages sent to that group include the witness
registration id and, for NTLM-authenticated mounts, the username, domain,
and password attributes copied from the CIFS session.  An unprivileged
local process should not be able to join that group and receive those
messages.

Require CAP_NET_ADMIN for incoming SWN_NOTIFY commands with
GENL_ADMIN_PERM, and require CAP_NET_ADMIN over the network namespace for
joining the SWN multicast group with GENL_MCAST_CAP_NET_ADMIN.  The
cifs.witness service runs with the privileges needed for both operations.

Fixes: fed979a7e082 ("cifs: Set witness notification handler for messages from userspace daemon")
Cc: stable@vger.kernel.org
Signed-off-by: Michael Bommarito <michael.bommarito@gmail.com>
Assisted-by: Claude:claude-opus-4-7
Signed-off-by: Steve French <stfrench@microsoft.com>

Since commit 340cea84f691c ("cifs: open files should not hold ref on
superblock"), cifs file only holds the dentry ref_cnt, the cifs file
close work(cfile->deferred) could be executed after unmounting, which
will trigger a warning in generic_shutdown_super:
 BUG: Dentry 00000000a14a6845{i=c,n=file}  still in use (1) [unmount of
 cifs cifs]

The detailed processs is:
   process A           process B           kworker
 fd = open(PATH)
  vfs_open
   file->__f_path = *path // dentry->d_lockref.count = 1
   cifs_open
    cifs_new_fileinfo
     cfile->dentry = dget(dentry) // dentry->d_lockref.count = 2
 close(fd)
  __fput
  cifs_close
   queue_delayed_work(deferredclose_wq, cfile->deferred)
  dput(dentry) // dentry->d_lockref.count = 1
			                 smb2_deferred_work_close
					  _cifsFileInfo_put
					   list_del(&cifs_file->flist)
                    umount
		     cleanup_mnt
		      deactivate_super
		       cifs_kill_sb
		        cifs_close_all_deferred_files_sb
			 cifs_close_all_deferred_files
			  // cannot find cfile, skip _cifsFileInfo_put
			kill_anon_super
			 generic_shutdown_super
			  shrink_dcache_for_umount
			   umount_check
			    WARN ! // dentry->d_lockref.count = 1
					   cifsFileInfo_put_final
					    dput(cifs_file->dentry)
		                            // dentry->d_lockref.count = 0

Fix it by flushing 'deferredclose_wq' before calling kill_anon_super.

Fetch a reproducer in https://bugzilla.kernel.org/show_bug.cgi?id=221548.

Fixes: 340cea84f691c ("cifs: open files should not hold ref on superblock")
Cc: stable@vger.kernel.org
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

In handle_read_data() the encrypted/folioq branch
(buf_len <= data_offset, reached via receive_encrypted_read for
transform PDUs > CIFSMaxBufSize + MAX_HEADER_SIZE) copies the READ
payload using buffer_len rather than data_len:

	rdata->result = cifs_copy_folioq_to_iter(buffer, buffer_len,
						 cur_off,
						 &rdata->subreq.io_iter);
	...
	rdata->got_bytes = buffer_len;

buffer_len comes from the SMB3 transform header OriginalMessageSize
field (OriginalMessageSize - read_rsp_size); it represents the size
of the decrypted message after the SMB2 header.  data_len comes from
the SMB2 READ response DataLength field; it represents the actual
READ payload size and may be smaller than buffer_len when the
decrypted message contains padding or other trailing bytes after the
READ payload.  The existing check `data_len > buffer_len - pad_len`
only enforces an upper bound, so a server that emits
OriginalMessageSize larger than read_rsp_size + pad_len + data_len
passes the check and the kernel copies buffer_len bytes per response,
ignoring the server-asserted DataLength.

Two observable failures with a crafted server (DataLength=4,
buffer_len=20000):

  - the kernel returns 20000 bytes per sub-request to userspace and
    sets got_bytes = buffer_len, even though the response claimed
    only 4 bytes of payload;

  - on a partial netfs sub-request whose iterator is sized to
    data_len, the over-large copy_folio_to_iter() short-reads,
    cifs_copy_folioq_to_iter() returns -EIO via the n != len path,
    and the entire netfs read collapses to -EIO even though the
    leading sub-requests succeeded.

Use data_len for the copy length and for got_bytes so the kernel
honours the server-asserted READ payload size.  For well-formed
servers (where buffer_len == pad_len + data_len) the change is
behaviour-equivalent.

Cc: stable@vger.kernel.org
Signed-off-by: Jeremy Erazo <mendozayt13@gmail.com>
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

cifs.spnego key descriptions contain authority-bearing fields such as
pid, uid, creduid, and upcall_target that cifs.upcall treats as
kernel-originating inputs. However, userspace can also create keys of
this type through request_key(2) or add_key(2), allowing those fields to
be supplied without CIFS origin.

Only accept cifs.spnego descriptions while CIFS is using its private
spnego_cred to request the key.

Fixes: f1d662a7d5e5 ("[CIFS] Add upcall files for cifs to use spnego/kerberos")
Assisted-by: avom-custom-harness:gpt-5.5-qwen3.6-mod-mix
Reviewed-by: David Howells <dhowells@redhat.com>
Signed-off-by: Asim Viladi Oglu Manizada <manizada@pm.me>
Signed-off-by: Steve French <stfrench@microsoft.com>

Commit 96c4af418586 ("cifs: Fix locking usage for tcon fields")
refactored cifs code to change cifs_tcp_ses_lock for tc_lock around
tc_count changes.

There was missing lock around tc_count increment inside
smb2_find_smb_sess_tcon_unlocked().

Cc: stable@vger.kernel.org
Fixes: 96c4af418586 ("cifs: Fix locking usage for tcon fields")
Reviewed-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Henrique Carvalho <henrique.carvalho@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

Fix a couple of undefined variables introduced by the patch to fix tearing
on ->remote_i_size and ->zero_point.  For some reason, make W=1 with gcc
doesn't give undefined variable warnings (but clang does).

Fixes: 2c8f4742bb76 ("netfs: Fix potential for tearing in ->remote_i_size and ->zero_point")
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202605031459.eX5UbO3K-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202605021450.ca5QGqLH-lkp@intel.com/
cc: Steve French <sfrench@samba.org>
cc: Paulo Alcantara <pc@manguebit.org>
cc: Matthew Wilcox <willy@infradead.org>
cc: Christian Brauner <brauner@kernel.org>
cc: linux-cifs@vger.kernel.org
cc: netfs@lists.linux.dev
cc: linux-fsdevel@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>