linux-kernel - Re: [PATCH] LoongArch: kexec: Initialize kexec

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Message-ID: <d327af2b-8089-4d1b-8f7f-9f18c0d9faba@linux.dev>
Date: Fri, 24 Oct 2025 15:06:56 +0800
From: Youling Tang <youling.tang@...ux.dev>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: kexec@...ts.infradead.org, Breno Leitao <leitao@...ian.org>,
 Youling Tang <tangyouling@...inos.cn>, loongarch@...ts.linux.dev,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] LoongArch: kexec: Initialize kexec_buf struct

cc to loongarch@...ts.linux.dev and linux-kernel@...r.kernel.org


On 10/24/25 14:36, Youling Tang wrote:
> From: Youling Tang <tangyouling@...inos.cn>
>
> 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.
>
> Fixes: bf454ec31add ("kexec_file: allow to place kexec_buf randomly")
> Link: https://lore.kernel.org/r/20250827-kbuf_all-v1-2-1df9882bb01a@debian.org
> Signed-off-by: Youling Tang <tangyouling@...inos.cn>
> ---
>   arch/loongarch/kernel/kexec_efi.c          | 2 +-
>   arch/loongarch/kernel/kexec_elf.c          | 2 +-
>   arch/loongarch/kernel/machine_kexec_file.c | 2 +-
>   3 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/loongarch/kernel/kexec_efi.c b/arch/loongarch/kernel/kexec_efi.c
> index 45121b914f8f..5ee78ebb1546 100644
> --- a/arch/loongarch/kernel/kexec_efi.c
> +++ b/arch/loongarch/kernel/kexec_efi.c
> @@ -42,7 +42,7 @@ static void *efi_kexec_load(struct kimage *image,
>   {
>   	int ret;
>   	unsigned long text_offset, kernel_segment_number;
> -	struct kexec_buf kbuf;
> +	struct kexec_buf kbuf = {};
>   	struct kexec_segment *kernel_segment;
>   	struct loongarch_image_header *h;
>   
> diff --git a/arch/loongarch/kernel/kexec_elf.c b/arch/loongarch/kernel/kexec_elf.c
> index 97b2f049801a..1b6b64744c7f 100644
> --- a/arch/loongarch/kernel/kexec_elf.c
> +++ b/arch/loongarch/kernel/kexec_elf.c
> @@ -59,7 +59,7 @@ static void *elf_kexec_load(struct kimage *image,
>   	int ret;
>   	unsigned long text_offset, kernel_segment_number;
>   	struct elfhdr ehdr;
> -	struct kexec_buf kbuf;
> +	struct kexec_buf kbuf = {};
>   	struct kexec_elf_info elf_info;
>   	struct kexec_segment *kernel_segment;
>   
> diff --git a/arch/loongarch/kernel/machine_kexec_file.c b/arch/loongarch/kernel/machine_kexec_file.c
> index dda236b51a88..fb57026f5f25 100644
> --- a/arch/loongarch/kernel/machine_kexec_file.c
> +++ b/arch/loongarch/kernel/machine_kexec_file.c
> @@ -143,7 +143,7 @@ int load_other_segments(struct kimage *image,
>   	unsigned long initrd_load_addr = 0;
>   	unsigned long orig_segments = image->nr_segments;
>   	char *modified_cmdline = NULL;
> -	struct kexec_buf kbuf;
> +	struct kexec_buf kbuf = {};
>   
>   	kbuf.image = image;
>   	/* Don't allocate anything below the kernel */