linux-kernel - Re: CVE-2023-52665: powerpc/ps3_defconfig: Disable PPC64_BIG_ENDIAN_ELF_ABI

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Date: Mon, 20 May 2024 10:52:00 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: Geoff Levand <geoff@...radead.org>,
	Michael Ellerman <mpe@...erman.id.au>, cve@...nel.org,
	linux-kernel@...r.kernel.org, linux-cve-announce@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org
Subject: Re: CVE-2023-52665: powerpc/ps3_defconfig: Disable
 PPC64_BIG_ENDIAN_ELF_ABI_V2

On Mon, May 20, 2024 at 05:35:32PM +0900, Geoff Levand wrote:
> On 5/20/24 16:04, Michael Ellerman wrote:
> > Greg Kroah-Hartman <gregkh@...uxfoundation.org> writes:
> >> Description
> >> ===========
> >>
> >> In the Linux kernel, the following vulnerability has been resolved:
> >>
> >> powerpc/ps3_defconfig: Disable PPC64_BIG_ENDIAN_ELF_ABI_V2
> >>
> >> Commit 8c5fa3b5c4df ("powerpc/64: Make ELFv2 the default for big-endian
> >> builds"), merged in Linux-6.5-rc1 changes the calling ABI in a way
> >> that is incompatible with the current code for the PS3's LV1 hypervisor
> >> calls.
> >>
> >> This change just adds the line '# CONFIG_PPC64_BIG_ENDIAN_ELF_ABI_V2 is not set'
> >> to the ps3_defconfig file so that the PPC64_ELF_ABI_V1 is used.
> >>
> >> Fixes run time errors like these:
> >>
> >>   BUG: Kernel NULL pointer dereference at 0x00000000
> >>   Faulting instruction address: 0xc000000000047cf0
> >>   Oops: Kernel access of bad area, sig: 11 [#1]
> >>   Call Trace:
> >>   [c0000000023039e0] [c00000000100ebfc] ps3_create_spu+0xc4/0x2b0 (unreliable)
> >>   [c000000002303ab0] [c00000000100d4c4] create_spu+0xcc/0x3c4
> >>   [c000000002303b40] [c00000000100eae4] ps3_enumerate_spus+0xa4/0xf8
> >>
> >> The Linux kernel CVE team has assigned CVE-2023-52665 to this issue.
> > 
> > IMHO this doesn't warrant a CVE. The crash mentioned above happens at
> > boot, so the system is not vulnerable it's just broken :)
> 
> As Greg says, with PPC64_BIG_ENDIAN_ELF_ABI_V2 enabled the system won't
> boot, so there is no chance of a vulnerability.

The definition of "vulnerability" from CVE.org is:
	An instance of one or more weaknesses in a Product that can be
	exploited, causing a negative impact to confidentiality, integrity, or
	availability; a set of conditions or behaviors that allows the
	violation of an explicit or implicit security policy.

Having a system that does not boot is a "negative impact to
availability", which is why this was selected for a CVE.  I.e. if a new
kernel update has this problem in it, it would not allow the system to
boot correctly.

But, if the maintainer of the subsystem thinks this should not be
assigned a CVE because of this fix, we'll be glad to revoke it.

Michael, still want this revoked?

thanks,

greg k-h