Received-SPF: pass (google.com: domain of linux-kernel+bounces-13387-linux.lists.archive=gmail.com@vger.kernel.org designates 139.178.88.99 as permitted sender) client-ip=139.178.88.99;
Date: Sat, 30 Dec 2023 18:28:06 +0800
From: Baoquan He <bhe@redhat.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Yuntao Wang <ytcoode@gmail.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: <ZY/wtvltzGR0CokV@MiWiFi-R3L-srv>
References: <20231218092902.9fae480cfcad3874e9e7236f@linux-foundation.org>
 <20231219163418.108591-1-ytcoode@gmail.com>
 <20231229121014.fd090f8c616a34fbb45f7843@linux-foundation.org>
Precedence: bulk
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20231229121014.fd090f8c616a34fbb45f7843@linux-foundation.org>

On 12/29/23 at 12:10pm, Andrew Morton wrote:
> 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?


I suggested this in below discussion thread:
https://lore.kernel.org/all/ZYEOshALGbDKwSdc@MiWiFi-R3L-srv/T/#u

So it would be good if squashing this into patch 3 of another patch
thread you are asking:
[PATCH 3/3] crash_core: fix and simplify the logic of crash_exclude_mem_range()

And I would suggest withdrawing Yuntao's below patch on your
mm-nonmm-unstable branch.

961c69e9f1bf x86/crash: fix potential cmem->ranges array overflow

Becase there's better one to fix the potential oob from fuqiang,
although fuqiang need improve his patch log.

[PATCH v3] x86/kexec: fix potential cmem->ranges out of bounds
https://lore.kernel.org/all/20231222121855.148215-1-fuqiang.wang@easystack.cn/T/#u

> 
> > --- 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
>