Merge tag 'v7.2-rc4-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6HEADmaster

Pull smb client fixes from Steve French:
 - Fix leak in cifs_close_deferred_file()
 - Fix resolving MacOS symlinks
 - Fix stale file size in readdir
 - Update git branches in MAINTAINERS file
 - Fix bounds check in cifs_filldir
 - Fix checks in parse_dfs_referrals()
 - Fix DFS referral checks for malformed packet

* tag 'v7.2-rc4-smb3-client-fixes' of git://git.samba.org/sfrench/cifs-2.6:
  cifs: fix cifsFileInfo leak on kmalloc failure in deferred close drain paths
  cifs: prevent readdir from changing file size due to stale directory metadata
  smb: client: handle STATUS_STOPPED_ON_SYMLINK responses without a symlink target
  Add missing git branch info for cifs and ksmbd to MAINTAINERS file
  smb: client: bound dirent name against end of SMB response in cifs_filldir
  smb: client: validate DFS referral PathConsumed

8 files changed, 208 insertions, 28 deletions

diff --git a/fs/smb/client/cifsfs.c b/fs/smb/client/cifsfs.c
index 66b9104e7ca2..1788d93a2522 100644
--- a/fs/smb/client/cifsfs.c
+++ b/fs/smb/client/cifsfs.c
@@ -440,6 +440,7 @@ cifs_alloc_inode(struct super_block *sb)
 		return NULL;
 	cifs_inode->cifsAttrs = ATTR_ARCHIVE;	/* default */
 	cifs_inode->time = 0;
+	cifs_inode->time_last_write = 0;
 	/*
 	 * Until the file is open and we have gotten oplock info back from the
 	 * server, can not assume caching of file data or metadata.
diff --git a/fs/smb/client/cifsglob.h b/fs/smb/client/cifsglob.h
index 08e94633a9c1..79e4e84f8985 100644
--- a/fs/smb/client/cifsglob.h
+++ b/fs/smb/client/cifsglob.h
@@ -1566,6 +1566,7 @@ struct cifsInodeInfo {
 	spinlock_t writers_lock;
 	unsigned int writers;		/* Number of writers on this inode */
 	unsigned long time;		/* jiffies of last update of inode */
+	unsigned long time_last_write;	/* jiffies of last writable close or truncate */
 	u64  uniqueid;			/* server inode number */
 	u64  createtime;		/* creation time on server */
 	__u8 lease_key[SMB2_LEASE_KEY_SIZE];	/* lease key for this inode */
diff --git a/fs/smb/client/file.c b/fs/smb/client/file.c
index 968740e7c9c3..b279a44be729 100644
--- a/fs/smb/client/file.c
+++ b/fs/smb/client/file.c
@@ -1423,11 +1423,21 @@ void smb2_deferred_work_close(struct work_struct *work)
 {
 	struct cifsFileInfo *cfile = container_of(work,
 			struct cifsFileInfo, deferred.work);
+	struct cifsInodeInfo *cinode = CIFS_I(d_inode(cfile->dentry));
 
-	spin_lock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
+	spin_lock(&cinode->deferred_lock);
 	cifs_del_deferred_close(cfile);
 	cfile->deferred_close_scheduled = false;
-	spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
+	spin_unlock(&cinode->deferred_lock);
+	/*
+	 * Refresh time_last_write immediately before the actual server close
+	 * so the protection window is anchored to the real close time, not
+	 * the earlier userspace close time stored by cifs_close().
+	 */
+	if (OPEN_FMODE(cfile->f_flags) & FMODE_WRITE) {
+		/* Pairs with smp_load_acquire() in is_size_safe_to_change(). */
+		smp_store_release(&cinode->time_last_write, jiffies);
+	}
 	_cifsFileInfo_put(cfile, true, false);
 }
 
@@ -1457,6 +1467,10 @@ int cifs_close(struct inode *inode, struct file *file)
 	if (file->private_data != NULL) {
 		cfile = file->private_data;
 		file->private_data = NULL;
+		if (file->f_mode & FMODE_WRITE) {
+			/* Pairs with smp_load_acquire() in is_size_safe_to_change(). */
+			smp_store_release(&cinode->time_last_write, jiffies);
+		}
 		dclose = kmalloc_obj(struct cifs_deferred_close);
 		if ((cfile->status_file_deleted == false) &&
 		    (smb2_can_defer_close(inode, dclose))) {
@@ -3225,13 +3239,26 @@ static int is_inode_writable(struct cifsInodeInfo *cifs_inode)
 bool is_size_safe_to_change(struct cifsInodeInfo *cifsInode, __u64 end_of_file,
 			    bool from_readdir)
 {
+	struct cifs_sb_info *cifs_sb;
+	unsigned long tlw;
+
 	if (!cifsInode)
 		return true;
 
+	cifs_sb = CIFS_SB(cifsInode);
+
 	if (is_inode_writable(cifsInode) ||
 		((cifsInode->oplock & CIFS_CACHE_RW_FLG) != 0 && from_readdir)) {
 		/* This inode is open for write at least once */
-		struct cifs_sb_info *cifs_sb = CIFS_SB(cifsInode);
+
+		/*
+		 * Readdir data is unreliable when we have writable handles or
+		 * an exclusive lease -- never allow it to change i_size, even
+		 * on direct-IO mounts where the server's directory metadata
+		 * can still lag behind the actual file state.
+		 */
+		if (from_readdir)
+			return false;
 
 		if (cifs_sb_flags(cifs_sb) & CIFS_MOUNT_DIRECT_IO) {
 			/* since no page cache to corrupt on directio
@@ -3243,8 +3270,40 @@ bool is_size_safe_to_change(struct cifsInodeInfo *cifsInode, __u64 end_of_file,
 			return true;
 
 		return false;
-	} else
-		return true;
+	}
+
+	/*
+	 * No writable handles open. Check whether we are within the attribute
+	 * cache validity window of a recent local modification.
+	 *
+	 * For the close() path: cifs_close() calls smp_store_release() on
+	 * time_last_write before _cifsFileInfo_put() removes the handle under
+	 * open_file_lock. That spin_unlock() is a store-release that pairs
+	 * with the spin_lock() (load-acquire) in is_inode_writable() above,
+	 * so if is_inode_writable() returned false the smp_load_acquire()
+	 * below is guaranteed to observe any time_last_write update from a
+	 * concurrent close().
+	 *
+	 * For the setattr/truncate paths: those callers use smp_store_release()
+	 * directly; the smp_load_acquire() below pairs with that store. There
+	 * is no shared lock between setattr and readdir, so this relies on
+	 * acquire-release semantics alone. The store propagation latency on
+	 * weakly-ordered architectures (nanoseconds) is negligible relative to
+	 * the acregmax window (seconds) and the readdir RPC round-trip
+	 * (milliseconds), making this a sound design choice in practice.
+	 *
+	 * time_last_write == 0 means the inode has never been written locally;
+	 * skip the window check to avoid false positives near boot time when
+	 * jiffies is still close to INITIAL_JIFFIES on 32-bit systems.
+	 */
+	if (from_readdir) {
+		/* Pairs with smp_store_release() at close and truncate sites. */
+		tlw = smp_load_acquire(&cifsInode->time_last_write);
+		if (tlw && time_before(jiffies, tlw + cifs_sb->ctx->acregmax))
+			return false;
+	}
+
+	return true;
 }
 
 void cifs_oplock_break(struct work_struct *work)
diff --git a/fs/smb/client/inode.c b/fs/smb/client/inode.c
index deed04dd9b91..b2806371bfde 100644
--- a/fs/smb/client/inode.c
+++ b/fs/smb/client/inode.c
@@ -237,6 +237,8 @@ cifs_fattr_to_inode(struct inode *inode, struct cifs_fattr *fattr,
 	if (is_size_safe_to_change(cifs_i, fattr->cf_eof, from_readdir)) {
 		i_size_write(inode, fattr->cf_eof);
 		inode->i_blocks = CIFS_INO_BLOCKS(fattr->cf_bytes);
+	} else if (from_readdir && i_size_read(inode) != fattr->cf_eof) {
+		cifs_i->time = 0;
 	}
 
 	if (S_ISLNK(fattr->cf_mode) && fattr->cf_symlink_target) {
@@ -3277,6 +3279,8 @@ cifs_setattr_unix(struct dentry *direntry, struct iattr *attrs)
 
 	if ((attrs->ia_valid & ATTR_SIZE) &&
 	    attrs->ia_size != i_size_read(inode)) {
+		/* Pairs with smp_load_acquire() in is_size_safe_to_change(). */
+		smp_store_release(&cifsInode->time_last_write, jiffies);
 		truncate_setsize(inode, attrs->ia_size);
 		netfs_resize_file(&cifsInode->netfs, attrs->ia_size, true);
 		fscache_resize_cookie(cifs_inode_cookie(inode), attrs->ia_size);
@@ -3478,6 +3482,8 @@ cifs_setattr_nounix(struct dentry *direntry, struct iattr *attrs)
 
 	if ((attrs->ia_valid & ATTR_SIZE) &&
 	    attrs->ia_size != i_size_read(inode)) {
+		/* Pairs with smp_load_acquire() in is_size_safe_to_change(). */
+		smp_store_release(&cifsInode->time_last_write, jiffies);
 		truncate_setsize(inode, attrs->ia_size);
 		netfs_resize_file(&cifsInode->netfs, attrs->ia_size, true);
 		fscache_resize_cookie(cifs_inode_cookie(inode), attrs->ia_size);
diff --git a/fs/smb/client/misc.c b/fs/smb/client/misc.c
index e4bac2a0b85d..6edebc0807ea 100644
--- a/fs/smb/client/misc.c
+++ b/fs/smb/client/misc.c
@@ -497,7 +497,7 @@ cifs_del_deferred_close(struct cifsFileInfo *cfile)
 void
 cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
 {
-	struct cifsFileInfo *cfile = NULL;
+	struct cifsFileInfo *cfile = NULL, *failed_cfile = NULL;
 	struct file_list *tmp_list, *tmp_next_list;
 	LIST_HEAD(file_head);
 
@@ -514,8 +514,10 @@ cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
 
 				tmp_list = kmalloc_obj(struct file_list,
 						       GFP_ATOMIC);
-				if (tmp_list == NULL)
+				if (tmp_list == NULL) {
+					failed_cfile = cfile;
 					break;
+				}
 				tmp_list->cfile = cfile;
 				list_add_tail(&tmp_list->list, &file_head);
 			}
@@ -523,8 +525,24 @@ cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
 	}
 	spin_unlock(&cifs_inode->open_file_lock);
 
+	if (failed_cfile) {
+		if (OPEN_FMODE(failed_cfile->f_flags) & FMODE_WRITE) {
+			/* Pairs with smp_load_acquire() in is_size_safe_to_change(). */
+			smp_store_release(&CIFS_I(d_inode(failed_cfile->dentry))->time_last_write,
+					  jiffies);
+		}
+		_cifsFileInfo_put(failed_cfile, false, false);
+	}
+
 	list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
-		_cifsFileInfo_put(tmp_list->cfile, false, false);
+		struct cifsFileInfo *cfile = tmp_list->cfile;
+
+		if (OPEN_FMODE(cfile->f_flags) & FMODE_WRITE) {
+			/* Pairs with smp_load_acquire() in is_size_safe_to_change(). */
+			smp_store_release(&CIFS_I(d_inode(cfile->dentry))->time_last_write,
+					  jiffies);
+		}
+		_cifsFileInfo_put(cfile, false, false);
 		list_del(&tmp_list->list);
 		kfree(tmp_list);
 	}
@@ -533,7 +551,7 @@ cifs_close_deferred_file(struct cifsInodeInfo *cifs_inode)
 void
 cifs_close_all_deferred_files(struct cifs_tcon *tcon)
 {
-	struct cifsFileInfo *cfile;
+	struct cifsFileInfo *cfile, *failed_cfile = NULL;
 	struct file_list *tmp_list, *tmp_next_list;
 	LIST_HEAD(file_head);
 
@@ -547,8 +565,10 @@ cifs_close_all_deferred_files(struct cifs_tcon *tcon)
 
 				tmp_list = kmalloc_obj(struct file_list,
 						       GFP_ATOMIC);
-				if (tmp_list == NULL)
+				if (tmp_list == NULL) {
+					failed_cfile = cfile;
 					break;
+				}
 				tmp_list->cfile = cfile;
 				list_add_tail(&tmp_list->list, &file_head);
 			}
@@ -556,8 +576,24 @@ cifs_close_all_deferred_files(struct cifs_tcon *tcon)
 	}
 	spin_unlock(&tcon->open_file_lock);
 
+	if (failed_cfile) {
+		if (OPEN_FMODE(failed_cfile->f_flags) & FMODE_WRITE) {
+			/* Pairs with smp_load_acquire() in is_size_safe_to_change(). */
+			smp_store_release(&CIFS_I(d_inode(failed_cfile->dentry))->time_last_write,
+					  jiffies);
+		}
+		_cifsFileInfo_put(failed_cfile, true, false);
+	}
+
 	list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
-		_cifsFileInfo_put(tmp_list->cfile, true, false);
+		struct cifsFileInfo *cfile = tmp_list->cfile;
+
+		if (OPEN_FMODE(cfile->f_flags) & FMODE_WRITE) {
+			/* Pairs with smp_load_acquire() in is_size_safe_to_change(). */
+			smp_store_release(&CIFS_I(d_inode(cfile->dentry))->time_last_write,
+					  jiffies);
+		}
+		_cifsFileInfo_put(cfile, true, false);
 		list_del(&tmp_list->list);
 		kfree(tmp_list);
 	}
@@ -604,7 +640,7 @@ void cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon,
 					   struct dentry *dentry)
 {
 	struct file_list *tmp_list, *tmp_next_list;
-	struct cifsFileInfo *cfile;
+	struct cifsFileInfo *cfile, *failed_cfile = NULL;
 	LIST_HEAD(file_head);
 
 	spin_lock(&tcon->open_file_lock);
@@ -617,16 +653,34 @@ void cifs_close_deferred_file_under_dentry(struct cifs_tcon *tcon,
 			spin_unlock(&CIFS_I(d_inode(cfile->dentry))->deferred_lock);
 
 			tmp_list = kmalloc_obj(struct file_list, GFP_ATOMIC);
-			if (tmp_list == NULL)
+			if (tmp_list == NULL) {
+				failed_cfile = cfile;
 				break;
+			}
 			tmp_list->cfile = cfile;
 			list_add_tail(&tmp_list->list, &file_head);
 		}
 	}
 	spin_unlock(&tcon->open_file_lock);
 
+	if (failed_cfile) {
+		if (OPEN_FMODE(failed_cfile->f_flags) & FMODE_WRITE) {
+			/* Pairs with smp_load_acquire() in is_size_safe_to_change(). */
+			smp_store_release(&CIFS_I(d_inode(failed_cfile->dentry))->time_last_write,
+					  jiffies);
+		}
+		_cifsFileInfo_put(failed_cfile, true, false);
+	}
+
 	list_for_each_entry_safe(tmp_list, tmp_next_list, &file_head, list) {
-		_cifsFileInfo_put(tmp_list->cfile, true, false);
+		struct cifsFileInfo *cfile = tmp_list->cfile;
+
+		if (OPEN_FMODE(cfile->f_flags) & FMODE_WRITE) {
+			/* Pairs with smp_load_acquire() in is_size_safe_to_change(). */
+			smp_store_release(&CIFS_I(d_inode(cfile->dentry))->time_last_write,
+					  jiffies);
+		}
+		_cifsFileInfo_put(cfile, true, false);
 		list_del(&tmp_list->list);
 		kfree(tmp_list);
 	}
@@ -682,6 +736,8 @@ parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size,
 	int i, rc = 0;
 	char *data_end;
 	struct dfs_referral_level_3 *ref;
+	unsigned int path_consumed;
+	size_t search_name_len;
 
 	if (rsp_size < sizeof(*rsp)) {
 		cifs_dbg(VFS | ONCE,
@@ -728,6 +784,7 @@ parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size,
 		rc = -ENOMEM;
 		goto parse_DFS_referrals_exit;
 	}
+	search_name_len = strlen(searchName);
 
 	/* collect necessary data from referrals */
 	for (i = 0; i < *num_of_nodes; i++) {
@@ -736,21 +793,34 @@ parse_dfs_referrals(struct get_dfs_referral_rsp *rsp, u32 rsp_size,
 		struct dfs_info3_param *node = (*target_nodes)+i;
 
 		node->flags = le32_to_cpu(rsp->DFSFlags);
+		path_consumed = le16_to_cpu(rsp->PathConsumed);
 		if (is_unicode) {
-			__le16 *tmp = kmalloc(strlen(searchName)*2 + 2,
-						GFP_KERNEL);
-			if (tmp == NULL) {
+			size_t search_name_utf16_len = search_name_len * 2 + 2;
+			__le16 *tmp;
+
+			if (path_consumed > search_name_utf16_len) {
+				rc = -EINVAL;
+				goto parse_DFS_referrals_exit;
+			}
+
+			tmp = kmalloc(search_name_utf16_len, GFP_KERNEL);
+			if (!tmp) {
 				rc = -ENOMEM;
 				goto parse_DFS_referrals_exit;
 			}
-			cifsConvertToUTF16((__le16 *) tmp, searchName,
+			cifsConvertToUTF16((__le16 *)tmp, searchName,
 					   PATH_MAX, nls_codepage, remap);
-			node->path_consumed = cifs_utf16_bytes(tmp,
-					le16_to_cpu(rsp->PathConsumed),
-					nls_codepage);
+			node->path_consumed = cifs_utf16_bytes(tmp, path_consumed,
+							       nls_codepage);
 			kfree(tmp);
-		} else
-			node->path_consumed = le16_to_cpu(rsp->PathConsumed);
+		} else {
+			if (path_consumed > search_name_len) {
+				rc = -EINVAL;
+				goto parse_DFS_referrals_exit;
+			}
+
+			node->path_consumed = path_consumed;
+		}
 
 		node->server_type = le16_to_cpu(ref->ServerType);
 		node->ref_flag = le16_to_cpu(ref->ReferralEntryFlags);
diff --git a/fs/smb/client/readdir.c b/fs/smb/client/readdir.c
index ee5996e6d7d8..32a75afca8f5 100644
--- a/fs/smb/client/readdir.c
+++ b/fs/smb/client/readdir.c
@@ -952,7 +952,7 @@ static bool cifs_dir_emit(struct dir_context *ctx,
 static int cifs_filldir(char *find_entry, struct file *file,
 			struct dir_context *ctx,
 			char *scratch_buf, unsigned int max_len,
-			struct cached_fid *cfid)
+			char *end_of_smb, struct cached_fid *cfid)
 {
 	struct cifsFileInfo *file_info = file->private_data;
 	struct super_block *sb = file_inode(file)->i_sb;
@@ -974,6 +974,11 @@ static int cifs_filldir(char *find_entry, struct file *file,
 		return -EINVAL;
 	}
 
+	if (de.name + de.namelen > end_of_smb) {
+		cifs_dbg(VFS, "search entry name extends past end of SMB\n");
+		return -EINVAL;
+	}
+
 	/* skip . and .. since we added them first */
 	if (cifs_entry_is_dot(&de, file_info->srch_inf.unicode))
 		return 0;
@@ -1194,7 +1199,7 @@ int cifs_readdir(struct file *file, struct dir_context *ctx)
 		 */
 		*tmp_buf = 0;
 		rc = cifs_filldir(current_entry, file, ctx,
-				  tmp_buf, max_len, cfid);
+				  tmp_buf, max_len, end_of_smb, cfid);
 		if (rc) {
 			if (rc > 0)
 				rc = 0;
diff --git a/fs/smb/client/smb2file.c b/fs/smb/client/smb2file.c
index 5ef919bce52d..f35b6488d810 100644
--- a/fs/smb/client/smb2file.c
+++ b/fs/smb/client/smb2file.c
@@ -30,6 +30,19 @@ static struct smb2_symlink_err_rsp *symlink_data(const struct kvec *iov)
 	u8 *end = (u8 *)err + iov->iov_len;
 	u32 len;
 
+	/*
+	 * Per [MS-SMB2] section 2.2.2, a STATUS_STOPPED_ON_SYMLINK response has to
+	 * carry a Symbolic Link Error Response, so ByteCount cannot be zero.  Some
+	 * servers (e.g. the macOS built-in SMB server) violate this and return an
+	 * empty error response, with both ErrorContextCount and ByteCount set to
+	 * zero, i.e. without the symlink target.  Detect this and return -ENODATA
+	 * so that callers can tell "server did not send the target" apart from a
+	 * malformed response, and retrieve the target with FSCTL_GET_REPARSE_POINT
+	 * instead.
+	 */
+	if (!err->ErrorContextCount && !le32_to_cpu(err->ByteCount))
+		return ERR_PTR(-ENODATA);
+
 	if (err->ErrorContextCount) {
 		struct smb2_error_context_rsp *p;
 
@@ -199,6 +212,14 @@ int smb2_open_file(const unsigned int xid, struct cifs_open_parms *oparms,
 			rc = smb2_parse_symlink_response(oparms->cifs_sb, &err_iov,
 							 oparms->path,
 							 &data->symlink_target);
+			/*
+			 * If smb2_parse_symlink_response returned -ENODATA then the
+			 * symlink_target was not sent. Treat this as if the SMB2_open()
+			 * failed with STATUS_IO_REPARSE_TAG_NOT_HANDLED status, which is
+			 * indicated by the -EIO errno.
+			 */
+			if (rc == -ENODATA)
+				rc = -EIO;
 			if (!rc) {
 				memset(&data->fi, 0, sizeof(data->fi));
 				oparms->create_options |= OPEN_REPARSE_POINT;
diff --git a/fs/smb/client/smb2inode.c b/fs/smb/client/smb2inode.c
index 6c9c229b91f6..213bc298cdf2 100644
--- a/fs/smb/client/smb2inode.c
+++ b/fs/smb/client/smb2inode.c
@@ -792,9 +792,19 @@ static int parse_create_response(struct cifs_open_info_data *data,
 		rc = smb2_parse_symlink_response(cifs_sb, iov,
 						 full_path,
 						 &data->symlink_target);
-		if (rc)
+		if (rc != 0 && rc != -ENODATA)
 			return rc;
-		tag = IO_REPARSE_TAG_SYMLINK;
+		/*
+		 * -ENODATA means that the response was parsed but did not contain
+		 * the symlink target at all (see symlink_data()).  Treat it like
+		 * STATUS_IO_REPARSE_TAG_NOT_HANDLED, which does not contain it
+		 * either: leave the tag unset and clear rc, so that the caller
+		 * retrieves the target with SMB2_OP_GET_REPARSE.
+		 */
+		if (rc == -ENODATA)
+			rc = 0;
+		else
+			tag = IO_REPARSE_TAG_SYMLINK;
 		reparse_point = true;
 		break;
 	case STATUS_SUCCESS:
@@ -987,7 +997,14 @@ int smb2_query_path_info(const unsigned int xid,
 				rc = -EOPNOTSUPP;
 		}
 
-		if (data->reparse.tag == IO_REPARSE_TAG_SYMLINK && !rc) {
+		/*
+		 * If the symlink was already parsed in create response then it is needed to fix
+		 * its type now (after the second call with OPEN_REPARSE_POINT which filled the
+		 * data->fi.Attributes). If the symlink was not parsed in create response then
+		 * the data->symlink_target was not filled yet and then the type will be fixed
+		 * later after data->symlink_target is filled.
+		 */
+		if (data->reparse.tag == IO_REPARSE_TAG_SYMLINK && !rc && data->symlink_target) {
 			bool directory = le32_to_cpu(data->fi.Attributes) & ATTR_DIRECTORY;
 			rc = smb2_fix_symlink_target_type(&data->symlink_target, directory, cifs_sb);
 		}