Subject: CVE-2024-27069: ovl: relax WARN_ON in ovl_verify_area()

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

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

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

ovl: relax WARN_ON in ovl_verify_area()

syzbot hit an assertion in copy up data loop which looks like it is
the result of a lower file whose size is being changed underneath
overlayfs.

This type of use case is documented to cause undefined behavior, so
returning EIO error for the copy up makes sense, but it should not be
causing a WARN_ON assertion.

The Linux kernel CVE team has assigned CVE-2024-27069 to this issue.

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

	Issue introduced in 6.8 with commit ca7ab482401c and fixed in 6.8.2 with commit c3c85aefc0da
	Issue introduced in 6.8 with commit ca7ab482401c and fixed in 6.9 with commit 77a28aa47687

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-2024-27069
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/overlayfs/copy_up.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/c3c85aefc0da1e5074a06c682542a54ccc99bdca
	https://git.kernel.org/stable/c/77a28aa476873048024ad56daf8f4f17d58ee48e