linux-kernel - Re: [PATCH 0/3] kexec: Fix invalid field access

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Message-ID: <f7d55c91-8877-41aa-8cf0-64af38a9a109@ghiti.fr>
Date: Mon, 1 Sep 2025 08:42:51 +0200
From: Alexandre Ghiti <alex@...ti.fr>
To: Breno Leitao <leitao@...ian.org>,
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>,
 Andrew Morton <akpm@...ux-foundation.org>, Baoquan He <bhe@...hat.com>,
 Coiby Xu <coxu@...hat.com>, Paul Walmsley <paul.walmsley@...ive.com>,
 Palmer Dabbelt <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>,
 Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>,
 Alexander Gordeev <agordeev@...ux.ibm.com>,
 Christian Borntraeger <borntraeger@...ux.ibm.com>,
 Sven Schnelle <svens@...ux.ibm.com>
Cc: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-riscv@...ts.infradead.org, linux-s390@...r.kernel.org,
 kernel-team@...a.com
Subject: Re: [PATCH 0/3] kexec: Fix invalid field access

Hi Breno,

On 8/27/25 12:42, Breno Leitao wrote:
> The kexec_buf structure was previously declared without initialization.
> commit bf454ec31add ("kexec_file: allow to place kexec_buf randomly")
> added a field that is always read but not consistently populated by all
> architectures. This un-initialized field will contain garbage.
>
> This is also triggering a UBSAN warning when the uninitialized data was
> accessed:
>
> 	------------[ cut here ]------------
> 	UBSAN: invalid-load in ./include/linux/kexec.h:210:10
> 	load of value 252 is not a valid value for type '_Bool'
>
> Zero-initializing kexec_buf at declaration ensures all fields are
> cleanly set, preventing future instances of uninitialized memory being
> used.
>
> An initial fix was already landed for arm64[0], and this patchset fixes
> the problem on the remaining arm64 code and on riscv, as raised by Mark.
>
> Discussions about this problem could be found at[1][2].
>
> Link: https://lore.kernel.org/all/20250826180742.f2471131255ec1c43683ea07@linux-foundation.org/ [0]
> Link: https://lore.kernel.org/all/oninomspajhxp4omtdapxnckxydbk2nzmrix7rggmpukpnzadw@c67o7njgdgm3/ [1]
> Link: https://lore.kernel.org/all/20250826-akpm-v1-1-3c831f0e3799@debian.org/ [2]
>
> Signed-off-by: Breno Leitao <leitao@...ian.org>
> ---
> Breno Leitao (3):
>        arm64: kexec: Initialize kexec_buf struct in load_other_segments()
>        riscv: kexec: Initialize kexec_buf struct
>        s390: kexec: Initialize kexec_buf struct
>
>   arch/arm64/kernel/machine_kexec_file.c | 2 +-
>   arch/riscv/kernel/kexec_elf.c          | 4 ++--
>   arch/riscv/kernel/kexec_image.c        | 2 +-
>   arch/riscv/kernel/machine_kexec_file.c | 2 +-
>   arch/s390/kernel/kexec_elf.c           | 2 +-
>   arch/s390/kernel/kexec_image.c         | 2 +-
>   arch/s390/kernel/machine_kexec_file.c  | 6 +++---
>   7 files changed, 10 insertions(+), 10 deletions(-)
> ---
> base-commit: 3c642997252eef4449cb6b6e02af3dc22515d817
> change-id: 20250827-kbuf_all-b9d55c9291eb
>
> Best regards,
> --
> Breno Leitao <leitao@...ian.org>

I see that the commit those patches fix is in 6.16 so we should add cc: 
stable.

And who should merge those patches? Should we do it on a per-arch basis?

Thanks,

Alex

>
> _______________________________________________
> linux-riscv mailing list
> linux-riscv@...ts.infradead.org
> http://lists.infradead.org/mailman/listinfo/linux-riscv

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