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From: Andrew Morton <akpm@linux-foundation.org>
To: Alexey Dobriyan <adobriyan@gmail.com>
Cc: linux-kernel@vger.kernel.org, avagin@virtuozzo.com,
	viro@zeniv.linux.org.uk
Subject: Re: [PATCH v2] proc: fix /proc/*/map_files lookup some more
Date: Wed, 21 Feb 2018 12:04:03 -0800	[thread overview]
Message-ID: <20180221120403.504b7f1c814618bac39bb78b@linux-foundation.org> (raw)
In-Reply-To: <20180221195340.GA28911@avx2>

On Wed, 21 Feb 2018 22:53:40 +0300 Alexey Dobriyan <adobriyan@gmail.com> wrote:

> I totally forgot that _parse_integer() accepts arbitrary amount of
> leading zeroes leading to the following:
> 
> 		OK
> 	# readlink /proc/1/map_files/56427ecba000-56427eddc000
> 	/lib/systemd/systemd
> 
> 		bogus
> 	# readlink /proc/1/map_files/00000000000056427ecba000-56427eddc000
> 	/lib/systemd/systemd
> 	# readlink /proc/1/map_files/56427ecba000-00000000000056427eddc000
> 	/lib/systemd/systemd
> 
> ...
> 
> --- a/fs/proc/base.c
> +++ b/fs/proc/base.c
> @@ -1916,6 +1916,8 @@ static int dname_to_vma_addr(struct dentry *dentry,
>  	unsigned long long sval, eval;
>  	unsigned int len;
>  
> +	if (str[0] == '0' && str[1])
> +		return -EINVAL;
>  	len = _parse_integer(str, 16, &sval);
>  	if (len & KSTRTOX_OVERFLOW)
>  		return -EINVAL;
> @@ -1927,6 +1929,8 @@ static int dname_to_vma_addr(struct dentry *dentry,
>  		return -EINVAL;
>  	str++;
>  
> +	if (str[0] == '0' && str[1])
> +		return -EINVAL;
>  	len = _parse_integer(str, 16, &eval);
>  	if (len & KSTRTOX_OVERFLOW)
>  		return -EINVAL;

I don't know this code and I'm all confused.

- why is the code designed to accept addresses of "0"?

- how do we know that the first digit of a VMA address will never be 0?

  reply	other threads:[~2018-02-21 20:04 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-02-21 18:44 [PATCH] proc: fix /proc/*/map_files lookup some more Alexey Dobriyan
2018-02-21 18:51 ` Al Viro
2018-02-21 19:53   ` [PATCH v2] " Alexey Dobriyan
2018-02-21 20:04     ` Andrew Morton [this message]
2018-02-21 20:29       ` Cyrill Gorcunov
2018-02-21 20:58       ` Alexey Dobriyan
2018-03-03 21:51 Alexey Dobriyan
2018-03-04 20:53 ` Cyrill Gorcunov

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