CVE-2023-52496: mtd: maps: vmu-flash: Fix the (mtd core) switch to ref counters

CVE-2023-52496: mtd: maps: vmu-flash: Fix the (mtd core) switch to ref counters

[Lee Jones]

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

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

mtd: maps: vmu-flash: Fix the (mtd core) switch to ref counters

While switching to ref counters for track mtd devices use, the vmu-flash
driver was forgotten. The reason for reading the ref counter seems
debatable, but let's just fix the build for now.

The Linux kernel CVE team has assigned CVE-2023-52496 to this issue.


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

	Issue introduced in 6.6 with commit 19bfa9ebebb5 and fixed in 6.6.15 with commit 38c12f10990a
	Issue introduced in 6.6 with commit 19bfa9ebebb5 and fixed in 6.7.3 with commit 1168d6b79d2f
	Issue introduced in 6.6 with commit 19bfa9ebebb5 and fixed in 6.8-rc1 with commit a7d84a2e7663

Please see https://www.kernel.org or 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-2023-52496
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/maps/vmu-flash.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/38c12f10990ad6e63ddef2f20c1b066e5e4d34fd
	https://git.kernel.org/stable/c/1168d6b79d2fafb41299fbc1b528e20644c562a5
	https://git.kernel.org/stable/c/a7d84a2e7663bbe12394cc771107e04668ea313a

Re: CVE-2023-52496: mtd: maps: vmu-flash: Fix the (mtd core) switch to ref counters

[Michal Hocko]

On Thu 29-02-24 15:52:56, Lee Jones wrote:
> Description
> ===========
> 
> In the Linux kernel, the following vulnerability has been resolved:
> 
> mtd: maps: vmu-flash: Fix the (mtd core) switch to ref counters
> 
> While switching to ref counters for track mtd devices use, the vmu-flash
> driver was forgotten. The reason for reading the ref counter seems
> debatable, but let's just fix the build for now.

Do we really consider build fixes as CVE? 
-- 
Michal Hocko
SUSE Labs

Re: CVE-2023-52496: mtd: maps: vmu-flash: Fix the (mtd core) switch to ref counters

[Robert Frohl]

[-- Attachment #1.1.1: Type: text/plain, Size: 2552 bytes --]

Hi all,

 > but let's just fix the build for now.

Reads like it is only a build fix, does it really need a CVE ?

Thanks,
Robert

On 29.02.24 16:52, Lee Jones wrote:
> Description
> ===========
> 
> In the Linux kernel, the following vulnerability has been resolved:
> 
> mtd: maps: vmu-flash: Fix the (mtd core) switch to ref counters
> 
> While switching to ref counters for track mtd devices use, the vmu-flash
> driver was forgotten. The reason for reading the ref counter seems
> debatable, but let's just fix the build for now.
> 
> The Linux kernel CVE team has assigned CVE-2023-52496 to this issue.
> 
> 
> Affected and fixed versions
> ===========================
> 
> 	Issue introduced in 6.6 with commit 19bfa9ebebb5 and fixed in 6.6.15 with commit 38c12f10990a
> 	Issue introduced in 6.6 with commit 19bfa9ebebb5 and fixed in 6.7.3 with commit 1168d6b79d2f
> 	Issue introduced in 6.6 with commit 19bfa9ebebb5 and fixed in 6.8-rc1 with commit a7d84a2e7663
> 
> Please see https://www.kernel.org or 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-2023-52496
> 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/maps/vmu-flash.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/38c12f10990ad6e63ddef2f20c1b066e5e4d34fd
> 	https://git.kernel.org/stable/c/1168d6b79d2fafb41299fbc1b528e20644c562a5
> 	https://git.kernel.org/stable/c/a7d84a2e7663bbe12394cc771107e04668ea313a
> 

-- 
Security Engineer, SUSE Software Solutions Germany GmbH, Frankenstraße 
146, 90461 Nürnberg, Germany, GF: Ivo Totev, Andrew McDonald, Werner 
Knoblich (HRB 36809, AG Nürnberg)
GPG: D29F 82AA 9FD5 9D6E 74B1  6370 089E DB3D 230A 2404

[-- Attachment #1.1.2: OpenPGP public key --]
[-- Type: application/pgp-keys, Size: 12035 bytes --]

[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 840 bytes --]

Re: CVE-2023-52496: mtd: maps: vmu-flash: Fix the (mtd core) switch to ref counters

[Greg KH]

On Fri, Mar 08, 2024 at 11:08:51AM +0100, Michal Hocko wrote:
> On Thu 29-02-24 15:52:56, Lee Jones wrote:
> > Description
> > ===========
> > 
> > In the Linux kernel, the following vulnerability has been resolved:
> > 
> > mtd: maps: vmu-flash: Fix the (mtd core) switch to ref counters
> > 
> > While switching to ref counters for track mtd devices use, the vmu-flash
> > driver was forgotten. The reason for reading the ref counter seems
> > debatable, but let's just fix the build for now.
> 
> Do we really consider build fixes as CVE? 

Nope, good catch!  We reviewed this one wrong, now revoked, thanks for
the review.

greg k-h

Re: CVE-2023-52496: mtd: maps: vmu-flash: Fix the (mtd core) switch to ref counters

[Greg KH]

On Fri, Mar 08, 2024 at 11:26:54AM +0100, Robert Frohl wrote:
> Hi all,
> 
> > but let's just fix the build for now.
> 
> Reads like it is only a build fix, does it really need a CVE ?

You're a bit late:
	https://lore.kernel.org/all/2024030813-subscribe-smasher-aeca@gregkh/
:)

Already revoked, thanks for the review!

greg k-h