kmalloc a few large stack objects in the btrfs_ioctl path

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

1 files changed, 42 insertions, 18 deletions

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)