linux-cve-announce - CVE-2025-71184: btrfs: fix NULL dereference on root when tracing inode eviction

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Message-ID: <2026013134-CVE-2025-71184-e27f@gregkh>
Date: Sat, 31 Jan 2026 12:39:35 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2025-71184: btrfs: fix NULL dereference on root when tracing inode eviction

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

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

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

btrfs: fix NULL dereference on root when tracing inode eviction

When evicting an inode the first thing we do is to setup tracing for it,
which implies fetching the root's id. But in btrfs_evict_inode() the
root might be NULL, as implied in the next check that we do in
btrfs_evict_inode().

Hence, we either should set the ->root_objectid to 0 in case the root is
NULL, or we move tracing setup after checking that the root is not
NULL. Setting the rootid to 0 at least gives us the possibility to trace
this call even in the case when the root is NULL, so that's the solution
taken here.

The Linux kernel CVE team has assigned CVE-2025-71184 to this issue.


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

	Issue introduced in 2.6.39 with commit 1abe9b8a138c9988ba8f7bfded6453649a31541f and fixed in 6.12.66 with commit 582ba48e4a4c06fef6bdcf4e57b7b9af660bbd0c
	Issue introduced in 2.6.39 with commit 1abe9b8a138c9988ba8f7bfded6453649a31541f and fixed in 6.18.6 with commit 99e057f3d3ef24b99a7b1d84e01dd1bd890098da
	Issue introduced in 2.6.39 with commit 1abe9b8a138c9988ba8f7bfded6453649a31541f and fixed in 6.19-rc5 with commit f157dd661339fc6f5f2b574fe2429c43bd309534

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-2025-71184
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:
	include/trace/events/btrfs.h


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/582ba48e4a4c06fef6bdcf4e57b7b9af660bbd0c
	https://git.kernel.org/stable/c/99e057f3d3ef24b99a7b1d84e01dd1bd890098da
	https://git.kernel.org/stable/c/f157dd661339fc6f5f2b574fe2429c43bd309534