Hello,
On Mon, Mar 02, 2020 at 05:39:00PM -0800, Daniel Xu wrote:
> +static int kernfs_vfs_user_xattr_set(const struct xattr_handler *handler,
> + struct dentry *unused, struct inode *inode,
> + const char *suffix, const void *value,
> + size_t size, int flags)
> +{
...
> + if (value && atomic_inc_return(nr) > KERNFS_MAX_USER_XATTRS) {
> + ret = -ENOSPC;
> + goto dec_out;
> + }
So, we limit the number of user xattrs here but
> + ret = kernfs_vfs_xattr_set(handler, unused, inode, suffix, value,
> + size, flags);
This will call into simple_xattr_set() which doesn't put any further
restriction on size and just calls GFP_KERNEL kmalloc on it allowing
users incur high-order allocations. Maybe it'd make sense to limit
both the number and size?
Thanks.
--
tejun
