linux-cve-announce - CVE-2024-57934: fgraph: Add READ_ONCE() when accessing fgraph

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Message-ID: <2025012148-CVE-2024-57934-6cd8@gregkh>
Date: Tue, 21 Jan 2025 13:01:48 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2024-57934: fgraph: Add READ_ONCE() when accessing fgraph_array[]

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

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

fgraph: Add READ_ONCE() when accessing fgraph_array[]

In __ftrace_return_to_handler(), a loop iterates over the fgraph_array[]
elements, which are fgraph_ops. The loop checks if an element is a
fgraph_stub to prevent using a fgraph_stub afterward.

However, if the compiler reloads fgraph_array[] after this check, it might
race with an update to fgraph_array[] that introduces a fgraph_stub. This
could result in the stub being processed, but the stub contains a null
"func_hash" field, leading to a NULL pointer dereference.

To ensure that the gops compared against the fgraph_stub matches the gops
processed later, add a READ_ONCE(). A similar patch appears in commit
63a8dfb ("function_graph: Add READ_ONCE() when accessing fgraph_array[]").

The Linux kernel CVE team has assigned CVE-2024-57934 to this issue.

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

	Issue introduced in 6.11 with commit 37238abe3cb47b8daaa8706c9949f67b2a705cf1 and fixed in 6.12.9 with commit b68b2a3fbacc7be720ef589d489bcacdd05c6d38
	Issue introduced in 6.11 with commit 37238abe3cb47b8daaa8706c9949f67b2a705cf1 and fixed in 6.13 with commit d65474033740ded0a4fe9a097fce72328655b41d

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-2024-57934
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:
	kernel/trace/fgraph.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/b68b2a3fbacc7be720ef589d489bcacdd05c6d38
	https://git.kernel.org/stable/c/d65474033740ded0a4fe9a097fce72328655b41d