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

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Message-ID: <aK/RsVZxBw108MNJ@MiWiFi-R3L-srv>
Date: Thu, 28 Aug 2025 11:49:05 +0800
From: Baoquan He <bhe@...hat.com>
To: Breno Leitao <leitao@...ian.org>
Cc: Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Coiby Xu <coxu@...hat.com>,
	Paul Walmsley <paul.walmsley@...ive.com>,
	Palmer Dabbelt <palmer@...belt.com>,
	Albert Ou <aou@...s.berkeley.edu>, Alexandre Ghiti <alex@...ti.fr>,
	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>,
	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

On 08/27/25 at 03:42am, 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

Thanks for the fix, all looks good to me.

Acked-by: Baoquan He <bhe@...hat.com>