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Commit e4ad29fa authored by Vito Caputo's avatar Vito Caputo Committed by Miklos Szeredi
Browse files

ovl: use a minimal buffer in ovl_copy_xattr 

Rather than always allocating the high-order XATTR_SIZE_MAX buffer
which is costly and prone to failure, only allocate what is needed and
realloc if necessary.

Fixes https://github.com/coreos/bugs/issues/489



Signed-off-by: default avatarMiklos Szeredi <miklos@szeredi.hu>
Cc: <stable@vger.kernel.org>
parent 97daf8b9

fs/overlayfs/copy_up.c

+25 −14
Original line number Diff line number Diff line
@@ -22,9 +22,9 @@ 


int ovl_copy_xattr(struct dentry *old, struct dentry *new)

{

	ssize_t list_size, size;

	char *buf, *name, *value;

	int error;

	ssize_t list_size, size, value_size = 0;

	char *buf, *name, *value = NULL;

	int uninitialized_var(error);



	if (!old->d_inode->i_op->getxattr ||

	    !new->d_inode->i_op->getxattr)
@@ -41,29 +41,40 @@ int ovl_copy_xattr(struct dentry *old, struct dentry *new) 
	if (!buf)

		return -ENOMEM;



	error = -ENOMEM;

	value = kmalloc(XATTR_SIZE_MAX, GFP_KERNEL);

	if (!value)

		goto out;



	list_size = vfs_listxattr(old, buf, list_size);

	if (list_size <= 0) {

		error = list_size;

		goto out_free_value;

		goto out;

	}



	for (name = buf; name < (buf + list_size); name += strlen(name) + 1) {

		size = vfs_getxattr(old, name, value, XATTR_SIZE_MAX);

retry:

		size = vfs_getxattr(old, name, value, value_size);

		if (size == -ERANGE)

			size = vfs_getxattr(old, name, NULL, 0);



		if (size < 0) {

			error = size;

			goto out_free_value;

			break;

		}



		if (size > value_size) {

			void *new;



			new = krealloc(value, size, GFP_KERNEL);

			if (!new) {

				error = -ENOMEM;

				break;

			}

			value = new;

			value_size = size;

			goto retry;

		}



		error = vfs_setxattr(new, name, value, size, 0);

		if (error)

			goto out_free_value;

			break;

	}



out_free_value:

	kfree(value);

out:

	kfree(buf);