CVE-2026-64146: erofs: fix metabuf leak in inode xattr initialization

From: Greg Kroah-Hartman <[email protected]>

Description
===========

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

erofs: fix metabuf leak in inode xattr initialization

commit bb88e8da0025 ("erofs: use meta buffers for xattr operations")
converted xattr operations to use on-stack erofs_buf instances.
erofs_init_inode_xattrs() uses such a metabuf while reading the inline
xattr header and shared xattr id array.

Some error paths after erofs_read_metabuf() leave through out_unlock
without dropping the metabuf, so the folio reference can leak.

Consolidate the cleanup at out_unlock. erofs_put_metabuf() is a
no-op if no folio has been acquired, and this keeps all paths after
taking EROFS_I_BL_XATTR_BIT covered by a single cleanup site.

The Linux kernel CVE team has assigned CVE-2026-64146 to this issue.


Affected and fixed versions
===========================

	Issue introduced in 5.17 with commit bb88e8da00253bea0e7f0f4cdfd7910572d7799f and fixed in 7.0.11 with commit 492c73b21fefa36f3869cb2b188ffb7fe37b3a9b
	Issue introduced in 5.17 with commit bb88e8da00253bea0e7f0f4cdfd7910572d7799f and fixed in 7.1 with commit 79b09c54c6563df9846ca3094bcfd72082c3e1d7

Please see https://www.kernel.org for a full list of currently supported
kernel versions by the kernel community.

Unaffected versions might change over time as fixes are backported to
older supported kernel versions.  The official CVE entry at
	https://cve.org/CVERecord/?id=CVE-2026-64146
will be updated if fixes are backported, please check that for the most
up to date information about this issue.


Affected files
==============

The file(s) affected by this issue are:
	fs/erofs/xattr.c


Mitigation
==========

The Linux kernel CVE team recommends that you update to the latest
stable kernel version for this, and many other bugfixes.  Individual
changes are never tested alone, but rather are part of a larger kernel
release.  Cherry-picking individual commits is not recommended or
supported by the Linux kernel community at all.  If however, updating to
the latest release is impossible, the individual changes to resolve this
issue can be found at these commits:
	https://git.kernel.org/stable/c/492c73b21fefa36f3869cb2b188ffb7fe37b3a9b
	https://git.kernel.org/stable/c/79b09c54c6563df9846ca3094bcfd72082c3e1d7