pstore: inode: Use cleanup.h for struct pstore_private

Simplify error path when "private" needs to be freed.

Cc: Guilherme G. Piccoli <gpiccoli@igalia.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc:  <linux-hardening@vger.kernel.org>
Link: https://lore.kernel.org/r/20231205182622.1329923-4-keescook@chromium.org
Signed-off-by: Kees Cook <keescook@chromium.org>

Author: kees

fs/pstore/inode.c

@@ -63,6 +63,7 @@ static void free_pstore_private(struct pstore_private *private)
 	}
 	kfree(private);
 }
+DEFINE_FREE(pstore_private, struct pstore_private *, free_pstore_private(_T));
 
 static void *pstore_ftrace_seq_start(struct seq_file *s, loff_t *pos)
 {
@@ -340,9 +341,8 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 {
 	struct dentry		*dentry;
 	struct inode		*inode __free(pstore_iput) = NULL;
-	int			rc = 0;
 	char			name[PSTORE_NAMELEN];
-	struct pstore_private	*private, *pos;
+	struct pstore_private	*private __free(pstore_private) = NULL, *pos;
 	size_t			size = record->size + record->ecc_notice_size;
 
 	if (WARN_ON(!inode_is_locked(d_inode(root))))
@@ -358,7 +358,6 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 			return -EEXIST;
 	}
 
-	rc = -ENOMEM;
 	inode = pstore_get_inode(root->d_sb);
 	if (!inode)
 		return -ENOMEM;
@@ -375,7 +374,7 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 
 	dentry = d_alloc_name(root, name);
 	if (!dentry)
-		goto fail_private;
+		return -ENOMEM;
 
 	private->dentry = dentry;
 	private->record = record;
@@ -388,13 +387,9 @@ int pstore_mkfile(struct dentry *root, struct pstore_record *record)
 
 	d_add(dentry, no_free_ptr(inode));
 
-	list_add(&private->list, &records_list);
+	list_add(&(no_free_ptr(private))->list, &records_list);
 
 	return 0;
-
-fail_private:
-	free_pstore_private(private);
-	return rc;
 }
 
 /*