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Date: Fri, 29 Dec 2023 12:10:14 -0800
From: Andrew Morton <akpm@linux-foundation.org>
To: Yuntao Wang <ytcoode@gmail.com>
Cc: bhe@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
 dyoung@redhat.com, hbathini@linux.ibm.com, hpa@zytor.com,
 kexec@lists.infradead.org, linux-kernel@vger.kernel.org, mingo@redhat.com,
 seanjc@google.com, tglx@linutronix.de, tiwai@suse.de, vgoyal@redhat.com,
 x86@kernel.org
Subject: Re: [PATCH] crash_core: optimize crash_exclude_mem_range()
Message-Id: <20231229121014.fd090f8c616a34fbb45f7843@linux-foundation.org>
In-Reply-To: <20231219163418.108591-1-ytcoode@gmail.com>
References: <20231218092902.9fae480cfcad3874e9e7236f@linux-foundation.org>
	<20231219163418.108591-1-ytcoode@gmail.com>
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On Wed, 20 Dec 2023 00:34:18 +0800 Yuntao Wang <ytcoode@gmail.com> wrote:

> Because memory ranges in mem->ranges are stored in ascending order, when we
> detect `p_end < start`, we can break the for loop early, as the subsequent
> memory ranges must also be outside the range we are looking for.
> 
> Signed-off-by: Yuntao Wang <ytcoode@gmail.com>
> ---
> Hi Andrew,
> 
> Patch "[PATCH 2/2] crash_core: fix out-of-bounds access check in
> crash_exclude_mem_range()" can be ignored, use this patch instead.
> 

Some reviewer input on this would be helpful please?

> --- a/kernel/crash_core.c
> +++ b/kernel/crash_core.c
> @@ -575,9 +575,12 @@ int crash_exclude_mem_range(struct crash_mem *mem,
>  		p_start = mstart;
>  		p_end = mend;
>  
> -		if (p_start > end || p_end < start)
> +		if (p_start > end)
>  			continue;
>  
> +		if (p_end < start)
> +			break;
> +
>  		/* Truncate any area outside of range */
>  		if (p_start < start)
>  			p_start = start;
> -- 
> 2.43.0