linux-cve-announce - CVE-2023-53826: ubi: Fix UAF wear-leveling entry in eraseblk_count_seq

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Message-ID: <2025120951-CVE-2023-53826-26a2@gregkh>
Date: Tue,  9 Dec 2025 10:31:10 +0900
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-cve-announce@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...nel.org>
Subject: CVE-2023-53826: ubi: Fix UAF wear-leveling entry in eraseblk_count_seq_show()

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

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

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

ubi: Fix UAF wear-leveling entry in eraseblk_count_seq_show()

Wear-leveling entry could be freed in error path, which may be accessed
again in eraseblk_count_seq_show(), for example:

__erase_worker                eraseblk_count_seq_show
                                wl = ubi->lookuptbl[*block_number]
				if (wl)
  wl_entry_destroy
    ubi->lookuptbl[e->pnum] = NULL
    kmem_cache_free(ubi_wl_entry_slab, e)
		                   erase_count = wl->ec  // UAF!

Wear-leveling entry updating/accessing in ubi->lookuptbl should be
protected by ubi->wl_lock, fix it by adding ubi->wl_lock to serialize
wl entry accessing between wl_entry_destroy() and
eraseblk_count_seq_show().

Fetch a reproducer in [Link].

The Linux kernel CVE team has assigned CVE-2023-53826 to this issue.


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

	Issue introduced in 2.6.22 with commit 801c135ce73d5df1caf3eca35b66a10824ae0707 and fixed in 4.14.308 with commit 3f9b63dfce44a7c3c095dd93d910408e07ab1845
	Issue introduced in 2.6.22 with commit 801c135ce73d5df1caf3eca35b66a10824ae0707 and fixed in 4.19.276 with commit 84250da1c63cb7d421a3b4812b5c2ce2e47d31a1
	Issue introduced in 2.6.22 with commit 801c135ce73d5df1caf3eca35b66a10824ae0707 and fixed in 5.4.235 with commit 1cb14c06d6035539ef4215c4ba0871aea71d7c38
	Issue introduced in 2.6.22 with commit 801c135ce73d5df1caf3eca35b66a10824ae0707 and fixed in 5.10.173 with commit 9d448dd6bcb61a508204b57ea1f454ba9bac2f24
	Issue introduced in 2.6.22 with commit 801c135ce73d5df1caf3eca35b66a10824ae0707 and fixed in 5.15.100 with commit 79548ccdd992707879b4b683b7251c58ddf26f12
	Issue introduced in 2.6.22 with commit 801c135ce73d5df1caf3eca35b66a10824ae0707 and fixed in 6.1.18 with commit 84253f3c2dad6be10d30c92626c763d9a9f512ad
	Issue introduced in 2.6.22 with commit 801c135ce73d5df1caf3eca35b66a10824ae0707 and fixed in 6.2.5 with commit a100de2974d208cfca032179b02ed4d1a0a7f143
	Issue introduced in 2.6.22 with commit 801c135ce73d5df1caf3eca35b66a10824ae0707 and fixed in 6.3 with commit a240bc5c43130c6aa50831d7caaa02a1d84e1bce

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-2023-53826
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/mtd/ubi/wl.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/3f9b63dfce44a7c3c095dd93d910408e07ab1845
	https://git.kernel.org/stable/c/84250da1c63cb7d421a3b4812b5c2ce2e47d31a1
	https://git.kernel.org/stable/c/1cb14c06d6035539ef4215c4ba0871aea71d7c38
	https://git.kernel.org/stable/c/9d448dd6bcb61a508204b57ea1f454ba9bac2f24
	https://git.kernel.org/stable/c/79548ccdd992707879b4b683b7251c58ddf26f12
	https://git.kernel.org/stable/c/84253f3c2dad6be10d30c92626c763d9a9f512ad
	https://git.kernel.org/stable/c/a100de2974d208cfca032179b02ed4d1a0a7f143
	https://git.kernel.org/stable/c/a240bc5c43130c6aa50831d7caaa02a1d84e1bce