CVE-2024-47722: xen: use correct end address of kernel for conflict checking

CVE-2024-47722: xen: use correct end address of kernel for conflict checking

[Greg Kroah-Hartman]

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

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

xen: use correct end address of kernel for conflict checking

When running as a Xen PV dom0 the kernel is loaded by the hypervisor
using a different memory map than that of the host. In order to
minimize the required changes in the kernel, the kernel adapts its
memory map to that of the host. In order to do that it is checking
for conflicts of its load address with the host memory map.

Unfortunately the tested memory range does not include the .brk
area, which might result in crashes or memory corruption when this
area does conflict with the memory map of the host.

Fix the test by using the _end label instead of __bss_stop.

The Linux kernel CVE team has assigned CVE-2024-47722 to this issue.


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

	Issue introduced in 4.3 with commit 808fdb71936c and fixed in 5.10.227 with commit cb9134aa0998
	Issue introduced in 4.3 with commit 808fdb71936c and fixed in 5.15.168 with commit ed3e8cc9159a
	Issue introduced in 4.3 with commit 808fdb71936c and fixed in 6.1.113 with commit 6434af166441
	Issue introduced in 4.3 with commit 808fdb71936c and fixed in 6.6.54 with commit cafeba3c2a1f
	Issue introduced in 4.3 with commit 808fdb71936c and fixed in 6.10.13 with commit aee96b588070
	Issue introduced in 4.3 with commit 808fdb71936c and fixed in 6.11.2 with commit d9ab6bb136ad
	Issue introduced in 4.3 with commit 808fdb71936c and fixed in 6.12-rc1 with commit fac1bceeeb04

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-2024-47722
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:
	arch/x86/xen/setup.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/cb9134aa0998304a8521eafebe5ee486038698b3
	https://git.kernel.org/stable/c/ed3e8cc9159ae956fb0ac858496f66c803d5bbc8
	https://git.kernel.org/stable/c/6434af166441a998644ce961a630948ed5b986ba
	https://git.kernel.org/stable/c/cafeba3c2a1f015e26feb5629ae696e84cfb5ec9
	https://git.kernel.org/stable/c/aee96b588070609dbce40e80899019a6d264069f
	https://git.kernel.org/stable/c/d9ab6bb136adacc3c25de2032baf89bbad6ca7f8
	https://git.kernel.org/stable/c/fac1bceeeb04886fc2ee952672e6e6c85ce41dca

Re: CVE-2024-47722: xen: use correct end address of kernel for conflict checking

[Juergen Gross]

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On 21.10.24 14:16, Greg Kroah-Hartman wrote:
> Description
> ===========
> 
> In the Linux kernel, the following vulnerability has been resolved:
> 
> xen: use correct end address of kernel for conflict checking
> 
> When running as a Xen PV dom0 the kernel is loaded by the hypervisor
> using a different memory map than that of the host. In order to
> minimize the required changes in the kernel, the kernel adapts its
> memory map to that of the host. In order to do that it is checking
> for conflicts of its load address with the host memory map.
> 
> Unfortunately the tested memory range does not include the .brk
> area, which might result in crashes or memory corruption when this
> area does conflict with the memory map of the host.
> 
> Fix the test by using the _end label instead of __bss_stop.
> 
> The Linux kernel CVE team has assigned CVE-2024-47722 to this issue.

I fail to see how an unprivileged user could cause any harm here.

This bug is affecting the guest only, so only the guest admin can cause
harm to the guest at will via a special kernel. IMHO nothing CVE-worthy
here.

So I'd like to ask for this CVE being revoked.


Juergen

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Re: CVE-2024-47722: xen: use correct end address of kernel for conflict checking

[Greg Kroah-Hartman]

On Mon, Oct 21, 2024 at 02:35:16PM +0200, Juergen Gross wrote:
> On 21.10.24 14:16, Greg Kroah-Hartman wrote:
> > Description
> > ===========
> > 
> > In the Linux kernel, the following vulnerability has been resolved:
> > 
> > xen: use correct end address of kernel for conflict checking
> > 
> > When running as a Xen PV dom0 the kernel is loaded by the hypervisor
> > using a different memory map than that of the host. In order to
> > minimize the required changes in the kernel, the kernel adapts its
> > memory map to that of the host. In order to do that it is checking
> > for conflicts of its load address with the host memory map.
> > 
> > Unfortunately the tested memory range does not include the .brk
> > area, which might result in crashes or memory corruption when this
> > area does conflict with the memory map of the host.
> > 
> > Fix the test by using the _end label instead of __bss_stop.
> > 
> > The Linux kernel CVE team has assigned CVE-2024-47722 to this issue.
> 
> I fail to see how an unprivileged user could cause any harm here.
> 
> This bug is affecting the guest only, so only the guest admin can cause
> harm to the guest at will via a special kernel. IMHO nothing CVE-worthy
> here.

Ah, I thought this could affect the host, sorry about that.

> So I'd like to ask for this CVE being revoked.

Now revoked!

thanks for the review.

greg k-h