CVE-2026-72437: md/raid1: free r1_bio when REQ_NOWAIT is set and read would block on retry

CVE-2026-72437: md/raid1: free r1_bio when REQ_NOWAIT is set and read would block on retry

[Greg Kroah-Hartman]

From: Greg Kroah-Hartman <gregkh@kernel.org>

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

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

md/raid1: free r1_bio when REQ_NOWAIT is set and read would block on retry

When a read is retried, raid1_read_request() may be called with a
pre-allocated r1_bio. If wait_read_barrier() fails for a REQ_NOWAIT
read, the bio is completed and the function returns immediately. In this
case the existing r1_bio is leaked.

This fixes a leak of pre-allocated r1_bio structures for retried reads.

The Linux kernel CVE team has assigned CVE-2026-72437 to this issue.


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

	Issue introduced in 5.17 with commit 5aa705039c4fca84575539bfa2b8a28454a3d2ca and fixed in 6.1.178 with commit d1eda529a4bf6b866d02755723ee0eb1f037a5ed
	Issue introduced in 5.17 with commit 5aa705039c4fca84575539bfa2b8a28454a3d2ca and fixed in 6.6.145 with commit c66ed3e6371f5dba8f5d8ab810d6683ddc99201e
	Issue introduced in 5.17 with commit 5aa705039c4fca84575539bfa2b8a28454a3d2ca and fixed in 6.12.97 with commit db58075bc9c2ad2731f9c063859b47104bc2e7ef
	Issue introduced in 5.17 with commit 5aa705039c4fca84575539bfa2b8a28454a3d2ca and fixed in 6.18.40 with commit 6d92dbd73d19a0622f60352ce9d9379f7a760112
	Issue introduced in 5.17 with commit 5aa705039c4fca84575539bfa2b8a28454a3d2ca and fixed in 7.1.5 with commit c6e6354295845698d2fdfa20b71fc404786f7e93
	Issue introduced in 5.17 with commit 5aa705039c4fca84575539bfa2b8a28454a3d2ca and fixed in 7.2-rc1 with commit 69ad6ce47f9bf2b9fe0ed69b042db993d33bbf12

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-2026-72437
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:
	drivers/md/raid1.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/d1eda529a4bf6b866d02755723ee0eb1f037a5ed
	https://git.kernel.org/stable/c/c66ed3e6371f5dba8f5d8ab810d6683ddc99201e
	https://git.kernel.org/stable/c/db58075bc9c2ad2731f9c063859b47104bc2e7ef
	https://git.kernel.org/stable/c/6d92dbd73d19a0622f60352ce9d9379f7a760112
	https://git.kernel.org/stable/c/c6e6354295845698d2fdfa20b71fc404786f7e93
	https://git.kernel.org/stable/c/69ad6ce47f9bf2b9fe0ed69b042db993d33bbf12