kmalloc a few large stack objects in the btrfs_ioctl path

Signed-off-by: Chris Mason <chris.mason@oracle.com>

2 files changed, 56 insertions, 24 deletions

diff --git a/fs/btrfs/ctree.c b/fs/btrfs/ctree.c
index 585f279d1112..7f764455f26e 100644
--- a/fs/btrfs/ctree.c
+++ b/fs/btrfs/ctree.c
@@ -80,10 +80,14 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
         int ret = 0;
         int level;
         struct btrfs_key first_key;
-        struct btrfs_root new_root;
+        struct btrfs_root *new_root;
 
-        memcpy(&new_root, root, sizeof(new_root));
-        new_root.root_key.objectid = new_root_objectid;
+        new_root = kmalloc(sizeof(*new_root), GFP_NOFS);
+        if (!new_root)
+                return -ENOMEM;
+
+        memcpy(new_root, root, sizeof(*new_root));
+        new_root->root_key.objectid = new_root_objectid;
 
         WARN_ON(root->ref_cows && trans->transid !=
                 root->fs_info->running_transaction->transid);
@@ -99,12 +103,14 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
         } else {
                 first_key.objectid = 0;
         }
-        cow = __btrfs_alloc_free_block(trans, &new_root, buf->len,
+        cow = __btrfs_alloc_free_block(trans, new_root, buf->len,
                                        new_root_objectid,
                                        trans->transid, first_key.objectid,
                                        level, buf->start, 0);
-        if (IS_ERR(cow))
+        if (IS_ERR(cow)) {
+                kfree(new_root);
                 return PTR_ERR(cow);
+        }
 
         copy_extent_buffer(cow, buf, 0, 0, cow->len);
         btrfs_set_header_bytenr(cow, cow->start);
@@ -112,7 +118,9 @@ int btrfs_copy_root(struct btrfs_trans_handle *trans,
         btrfs_set_header_owner(cow, new_root_objectid);
 
         WARN_ON(btrfs_header_generation(buf) > trans->transid);
-        ret = btrfs_inc_ref(trans, &new_root, buf);
+        ret = btrfs_inc_ref(trans, new_root, buf);
+        kfree(new_root);
+
         if (ret)
                 return ret;
 
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 6a7d9160df27..1e725a48467c 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -2302,40 +2302,64 @@ out_unlock:
 
 static int btrfs_ioctl_snap_create(struct btrfs_root *root, void __user *arg)
 {
-        struct btrfs_ioctl_vol_args vol_args;
+        struct btrfs_ioctl_vol_args *vol_args;
         struct btrfs_dir_item *di;
         struct btrfs_path *path;
-        int namelen;
         u64 root_dirid;
+        int namelen;
+        int ret;
 
-        if (copy_from_user(&vol_args, arg, sizeof(vol_args)))
-                return -EFAULT;
+        vol_args = kmalloc(sizeof(*vol_args), GFP_NOFS);
 
-        namelen = strlen(vol_args.name);
-        if (namelen > BTRFS_VOL_NAME_MAX)
-                return -EINVAL;
-        if (strchr(vol_args.name, '/'))
-                return -EINVAL;
+        if (!vol_args)
+                return -ENOMEM;
+
+        if (copy_from_user(vol_args, arg, sizeof(*vol_args))) {
+                ret = -EFAULT;
+                goto out;
+        }
+
+        namelen = strlen(vol_args->name);
+        if (namelen > BTRFS_VOL_NAME_MAX) {
+                ret = -EINVAL;
+                goto out;
+        }
+        if (strchr(vol_args->name, '/')) {
+                ret = -EINVAL;
+                goto out;
+        }
 
         path = btrfs_alloc_path();
-        if (!path)
-                return -ENOMEM;
+        if (!path) {
+                ret = -ENOMEM;
+                goto out;
+        }
 
         root_dirid = root->fs_info->sb->s_root->d_inode->i_ino,
         mutex_lock(&root->fs_info->fs_mutex);
         di = btrfs_lookup_dir_item(NULL, root->fs_info->tree_root,
                             path, root_dirid,
-                            vol_args.name, namelen, 0);
+                            vol_args->name, namelen, 0);
         mutex_unlock(&root->fs_info->fs_mutex);
         btrfs_free_path(path);
-        if (di && !IS_ERR(di))
-                return -EEXIST;
-        if (IS_ERR(di))
-                return PTR_ERR(di);
+
+        if (di && !IS_ERR(di)) {
+                ret = -EEXIST;
+                goto out;
+        }
+
+        if (IS_ERR(di)) {
+                ret = PTR_ERR(di);
+                goto out;
+        }
 
         if (root == root->fs_info->tree_root)
-                return create_subvol(root, vol_args.name, namelen);
-        return create_snapshot(root, vol_args.name, namelen);
+                ret = create_subvol(root, vol_args->name, namelen);
+        else
+                ret = create_snapshot(root, vol_args->name, namelen);
+out:
+        kfree(vol_args);
+        return ret;
 }
 
 static int btrfs_ioctl_defrag(struct file *file)