linux-cve-announce - CVE-2025-21671: zram: fix potential UAF of zram table

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Message-ID: <2025013159-CVE-2025-21671-c4b0@gregkh>
Date: Fri, 31 Jan 2025 12:31:03 +0100
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: CVE-2025-21671: zram: fix potential UAF of zram table

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

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

zram: fix potential UAF of zram table

If zram_meta_alloc failed early, it frees allocated zram->table without
setting it NULL.  Which will potentially cause zram_meta_free to access
the table if user reset an failed and uninitialized device.

The Linux kernel CVE team has assigned CVE-2025-21671 to this issue.


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

	Issue introduced in 6.1.122 with commit ac3b5366b9b7c9d97b606532ceab43d2329a22f3 and fixed in 6.1.127 with commit fe3de867f94819ba0f28e035c0b0182150147d95
	Issue introduced in 6.6.68 with commit 0b5b0b65561b34e6e360de317e4bcd031bfabf42 and fixed in 6.6.74 with commit 571d3f6045cd3a6d9f6aec33b678f3ffe97582ef
	Issue introduced in 6.12.7 with commit 6fb92e9a52e3feae309a213950f21dfcd1eb0b40 and fixed in 6.12.11 with commit 902ef8f16d5ca77edc77c30656be54186c1e99b7

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-2025-21671
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/block/zram/zram_drv.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/fe3de867f94819ba0f28e035c0b0182150147d95
	https://git.kernel.org/stable/c/571d3f6045cd3a6d9f6aec33b678f3ffe97582ef
	https://git.kernel.org/stable/c/902ef8f16d5ca77edc77c30656be54186c1e99b7
	https://git.kernel.org/stable/c/212fe1c0df4a150fb6298db2cfff267ceaba5402