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From: Richard Weinberger <richard@nod.at>
To: yang.yang29@zte.com.cn
Cc: wang.yi59@zte.com.cn, richard.weinberger@gmail.com,
	linux-kernel@vger.kernel.org, linux-mtd@lists.infradead.org,
	xue.zhihong@zte.com.cn, dwmw2@infradead.org
Subject: Re: [PATCH] jffs2: check dstlen for jffs2_zlib_compress()
Date: Mon, 21 Jan 2019 12:35:24 +0100	[thread overview]
Message-ID: <3151900.SLYxvDXFDr@blindfold> (raw)
In-Reply-To: <201901211659107381808@zte.com.cn>

Am Montag, 21. Januar 2019, 09:59:10 CET schrieb yang.yang29@zte.com.cn:
> Thanks for reply.
> But I think if (*dstlen < 2) is not good enough.

Not enough in terms of what?
My patch does what the commit message says, it fixes the out of bound access.
What do I miss?

> Because if  the length of data_in is equals to 2, the length of output compressed data is also 2.
> So there's no meaning to do all the compress calculates.
> 
> And I had do an experiment:
> If dstlen equals to 3, and data_in has 3 same bytes, the length of output compressed data will be 2. 
> Which means compress is effective.

This is a different issue and a possible further optimization.

Thanks,
//richard




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WARNING: multiple messages have this Message-ID (diff)
From: Richard Weinberger <richard@nod.at>
To: yang.yang29@zte.com.cn
Cc: richard.weinberger@gmail.com, dwmw2@infradead.org,
	wang.yi59@zte.com.cn, linux-mtd@lists.infradead.org,
	linux-kernel@vger.kernel.org, xue.zhihong@zte.com.cn
Subject: Re: [PATCH] jffs2: check dstlen for jffs2_zlib_compress()
Date: Mon, 21 Jan 2019 12:35:24 +0100	[thread overview]
Message-ID: <3151900.SLYxvDXFDr@blindfold> (raw)
In-Reply-To: <201901211659107381808@zte.com.cn>

Am Montag, 21. Januar 2019, 09:59:10 CET schrieb yang.yang29@zte.com.cn:
> Thanks for reply.
> But I think if (*dstlen < 2) is not good enough.

Not enough in terms of what?
My patch does what the commit message says, it fixes the out of bound access.
What do I miss?

> Because if  the length of data_in is equals to 2, the length of output compressed data is also 2.
> So there's no meaning to do all the compress calculates.
> 
> And I had do an experiment:
> If dstlen equals to 3, and data_in has 3 same bytes, the length of output compressed data will be 2. 
> Which means compress is effective.

This is a different issue and a possible further optimization.

Thanks,
//richard




       reply	other threads:[~2019-01-21 11:35 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <201901211659107381808@zte.com.cn>
2019-01-21 11:35 ` Richard Weinberger [this message]
2019-01-21 11:35   ` [PATCH] jffs2: check dstlen for jffs2_zlib_compress() Richard Weinberger
     [not found] <201903201046335762775@zte.com.cn>
2019-03-20 21:06 ` Richard Weinberger
2019-03-20 21:06   ` Richard Weinberger
2019-01-21  0:21 Yang Yang
2019-01-21  8:04 ` Richard Weinberger
2019-01-21  8:04   ` Richard Weinberger

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