On Fri, Mar 01, 2024 at 05:30:55PM +0100, Roberto Sassu wrote:

quoted

+/*
+ * Inner implementation of vfs_caps_to_xattr() which does not return an
+ * error if the rootid does not map into @dest_userns.
+ */
+static ssize_t __vfs_caps_to_xattr(struct mnt_idmap *idmap,
+				   struct user_namespace *dest_userns,
+				   const struct vfs_caps *vfs_caps,
+				   void *data, size_t size)
+{
+	struct vfs_ns_cap_data *ns_caps = data;
+	struct vfs_cap_data *caps = (struct vfs_cap_data *)ns_caps;
+	kuid_t rootkuid;
+	uid_t rootid;
+
+	memset(ns_caps, 0, size);

size -> sizeof(*ns_caps) (or an equivalent change)

This is zeroing out the passed buffer, so it should use the size passed
for the buffer. sizeof(*ns_caps) could potentially be more than the size
of the buffer.

Maybe it would be clearer if it was memset(data, 0, size)?

I was zeroing more (the size of the buffer passed to vfs_getxattr()).

Roberto