linux-kernel - Re: [PATCH 1/1] kexec_file: fix elfcorehdr digest exclusion when CONFIG_CRASH

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Message-ID: <20240805171720.3b661180@mordecai.tesarici.cz>
Date: Mon, 5 Aug 2024 17:17:20 +0200
From: Petr Tesarik <petr.tesarik@...e.com>
To: Petr Tesarik <petr.tesarik@...e.com>
Cc: Eric Biederman <ebiederm@...ssion.com>, Sourabh Jain
 <sourabhjain@...ux.ibm.com>, Hari Bathini <hbathini@...ux.ibm.com>, Baoquan
 He <bhe@...hat.com>, Andrew Morton <akpm@...ux-foundation.org>, Eric
 DeVolder <eric_devolder@...oo.com>, kexec@...ts.infradead.org (open
 list:KEXEC), linux-kernel@...r.kernel.org (open list), stable@...nel.org
Subject: Re: [PATCH 1/1] kexec_file: fix elfcorehdr digest exclusion when
 CONFIG_CRASH_HOTPLUG=y

+Cc Eric DeVolder (current email address)

On Mon,  5 Aug 2024 17:07:50 +0200
Petr Tesarik <petr.tesarik@...e.com> wrote:

> From: Petr Tesarik <ptesarik@...e.com>
> 
> Fix the condition to exclude the elfcorehdr segment from the SHA digest
> calculation.
> 
> The j iterator is an index into the output sha_regions[] array, not into
> the input image->segment[] array. Once it reaches image->elfcorehdr_index,
> all subsequent segments are excluded. Besides, if the purgatory segment
> precedes the elfcorehdr segment, the elfcorehdr may be wrongly included in
> the calculation.
> 
> Fixes: f7cc804a9fd4 ("kexec: exclude elfcorehdr from the segment digest")
> Cc: stable@...nel.org
> Signed-off-by: Petr Tesarik <ptesarik@...e.com>
> ---
>  kernel/kexec_file.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c
> index 3d64290d24c9..3eedb8c226ad 100644
> --- a/kernel/kexec_file.c
> +++ b/kernel/kexec_file.c
> @@ -752,7 +752,7 @@ static int kexec_calculate_store_digests(struct kimage *image)
>  
>  #ifdef CONFIG_CRASH_HOTPLUG
>  		/* Exclude elfcorehdr segment to allow future changes via hotplug */
> -		if (j == image->elfcorehdr_index)
> +		if (i == image->elfcorehdr_index)
>  			continue;
>  #endif
>