xfs: in _attrlist_by_handle, copy the cursor back to userspace

BugLink: http://bugs.launchpad.net/bugs/1697001
commit 0facef7fb053be4353c0a48c2f48c9dbee91cb19 upstream.

When we're iterating inode xattrs by handle, we have to copy the
cursor back to userspace so that a subsequent invocation actually
retrieves subsequent contents.

Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Dave Chinner <david@fromorbit.com>
Cc: Nikolay Borisov <nborisov@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>

diff --git a/fs/xfs/xfs_ioctl.c b/fs/xfs/xfs_ioctl.c
index 08479daa6781d23365868363baabe4feb53e7652..e4a4f82ea13f919b800960312bc359cdc0997736 100644 (file)
--- a/fs/xfs/xfs_ioctl.c
+++ b/fs/xfs/xfs_ioctl.c
@@ -403,6 +403,7 @@ xfs_attrlist_by_handle(
 {
        int                     error = -ENOMEM;
        attrlist_cursor_kern_t  *cursor;
+       struct xfs_fsop_attrlist_handlereq __user       *p = arg;
        xfs_fsop_attrlist_handlereq_t al_hreq;
        struct dentry           *dentry;
        char                    *kbuf;
@@ -435,6 +436,11 @@ xfs_attrlist_by_handle(
        if (error)
                goto out_kfree;
 
+       if (copy_to_user(&p->pos, cursor, sizeof(attrlist_cursor_kern_t))) {
+               error = -EFAULT;
+               goto out_kfree;
+       }
+
        if (copy_to_user(al_hreq.buffer, kbuf, al_hreq.buflen))
                error = -EFAULT;