linux-kernel - Re: [PATCH 0/3] Use new wrappers to copy userspace arrays

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Date:   Thu, 30 Nov 2023 17:52:06 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Janosch Frank <frankja@...ux.ibm.com>,
        Claudio Imbrenda <imbrenda@...ux.ibm.com>,
        David Hildenbrand <david@...hat.com>,
        Heiko Carstens <hca@...ux.ibm.com>,
        Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Philipp Stanner <pstanner@...hat.com>
Cc:     kvm@...r.kernel.org, linux-s390@...r.kernel.org,
        linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: [PATCH 0/3] Use new wrappers to copy userspace arrays

On Thu, 02 Nov 2023 19:15:23 +0100, Philipp Stanner wrote:
> Linus recently merged [1] the wrapper functions memdup_array_user() and
> vmemdup_array_user() in include/linux/string.h for Kernel v6.7
> 
> I am currently adding them to all places where (v)memdup_user() had been
> used to copy arrays.
> 
> The wrapper is different to the wrapped functions only in that it might
> return -EOVERFLOW. So this new error code might get pushed up to
> userspace. I hope this is fine.
> 
> [...]

Applied to kvm-x86 generic.  Claudio (or anyone else from s390), holler if
you want to take the s390 patch through the s390 tree.

I massaged the shortlogs to use KVM's standard scopes, and to make it clear
that these are hardening patches, i.e. that there is no unsafe/buggy behavior
that is being fixed.  I also added a note at the end of each changelog to call
out that KVM pre-checks the sizes before copying, again to make it clear that
using the safer helper isn't expected to actually change KVM's behavior.

[1/3] KVM: x86: Harden copying of userspace-array against overflow
      https://github.com/kvm-x86/linux/commit/573cc0e5cf14
[2/3] KVM: s390: Harden copying of userspace-array against overflow
      https://github.com/kvm-x86/linux/commit/8b81a8d7c6b7
[3/3] KVM: Harden copying of userspace-array against overflow
      https://github.com/kvm-x86/linux/commit/bc2cad56094c

--
https://github.com/kvm-x86/linux/tree/next