Subject: CVE-2024-43832: s390/uv: Don't call folio_wait_writeback() without a folio reference

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

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

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

s390/uv: Don't call folio_wait_writeback() without a folio reference

folio_wait_writeback() requires that no spinlocks are held and that
a folio reference is held, as documented. After we dropped the PTL, the
folio could get freed concurrently. So grab a temporary reference.

The Linux kernel CVE team has assigned CVE-2024-43832 to this issue.

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

	Issue introduced in 5.7 with commit 214d9bbcd3a6 and fixed in 6.1.103 with commit 1a1eb2f3fc45
	Issue introduced in 5.7 with commit 214d9bbcd3a6 and fixed in 6.6.44 with commit 8736604ef533
	Issue introduced in 5.7 with commit 214d9bbcd3a6 and fixed in 6.10.3 with commit b21aba72aadd
	Issue introduced in 5.7 with commit 214d9bbcd3a6 and fixed in 6.11 with commit 3f29f6537f54

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-2024-43832
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:
	arch/s390/kernel/uv.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/1a1eb2f3fc453dcd52726d13e863938561489cb7
	https://git.kernel.org/stable/c/8736604ef53359a718c246087cd21dcec232d2fb
	https://git.kernel.org/stable/c/b21aba72aadd94bdac275deab021fc84d6c72b16
	https://git.kernel.org/stable/c/3f29f6537f54d74e64bac0a390fb2e26da25800d