CVE-2026-74358: ext4: fix fast commit wait/wake bit mapping on 64-bit

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

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

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

ext4: fix fast commit wait/wake bit mapping on 64-bit

On 64-bit, ext4 dynamic inode states live in the upper half of i_flags,
and ext4_test_inode_state() applies the corresponding +32 offset.

The fast-commit wait and wake paths open-coded the wait key with the raw
EXT4_STATE_* value. Add small helpers for the state wait word and bit,
and use them for the FC_COMMITTING and FC_FLUSHING_DATA waits so the wait
key follows the same mapping as the state helpers.

The Linux kernel CVE team has assigned CVE-2026-74358 to this issue.


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

	Issue introduced in 6.16 with commit 857d32f2618166765ce9306a246d0745afc76859 and fixed in 6.18.40 with commit e82d515092a0cf2bca92f399d5c330c324879cea
	Issue introduced in 6.16 with commit 857d32f2618166765ce9306a246d0745afc76859 and fixed in 7.1.5 with commit d06df6e447a8510f86db44b2522d5375362a9499
	Issue introduced in 6.16 with commit 857d32f2618166765ce9306a246d0745afc76859 and fixed in 7.2-rc1 with commit 8b3bc93fee6771775243665a0cf31857d6659775

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-2026-74358
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/ext4/ext4.h
	fs/ext4/fast_commit.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/e82d515092a0cf2bca92f399d5c330c324879cea
	https://git.kernel.org/stable/c/d06df6e447a8510f86db44b2522d5375362a9499
	https://git.kernel.org/stable/c/8b3bc93fee6771775243665a0cf31857d6659775