CVE-2026-64040

In the Linux kernel, the following vulnerability has been resolved:

cachefiles: Fix error return when vfs_mkdir() fails

When vfs_mkdir() fails, the error code is not extracted from the
returned error pointer. This causes mkdir_error to be reached with
ret=0, which leads to returning ERR_PTR(0) (NULL) instead of a
proper error pointer.

Fix this by extracting the error code from the error pointer when
vfs_mkdir() fails.