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From: XIAO Gang <xiao@unice.fr>
To: linux-kernel@vger.kernel.org
Subject: Suggestion on "int len" sanity
Date: Wed, 01 Jun 2005 09:06:33 +0200	[thread overview]
Message-ID: <429D5E79.2010707@unice.fr> (raw)


I would like to make a security suggestion.

There are many length variables in the kernel, locally declared as "len" 
or "length", either as "int", "unsigned int" or "size_t". However, 
declaring a length as "int" leads easily to an erroneous situation, as 
the author (or even a code checker) might make the implicite hypothesis 
that the length is positive, so that it is enough to make a sanity check 
of the kind

if (length > limit) ERROR;

which is not enough.

On the other hand, when a variable is named "len" or "length", it is 
usually used for length and never should go negative. So could I suggest 
that the declarations of these variables to be uniformized to "size_t", 
via a gradual but sysmatic cleanup?

-- 

XIAO Gang (~{P$8U~})                          xiao@unice.fr
          home page: pcmath126.unice.fr/xiao.html 




             reply	other threads:[~2005-06-01  7:06 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2005-06-01  7:06 XIAO Gang [this message]
2005-06-01 13:46 ` Suggestion on "int len" sanity Jörn Engel
2005-06-01 20:39 ` Willy Tarreau
2005-06-03  9:42   ` Geert Uytterhoeven
2005-06-03 12:47     ` Takashi Iwai
  -- strict thread matches above, loose matches on Subject: below --
2005-06-02  7:28 XIAO Gang
2005-06-02  8:48 ` Jörn Engel
2005-06-02  9:12   ` XIAO Gang
2005-06-02  9:47     ` Jörn Engel
2005-06-03  9:45   ` Geert Uytterhoeven
2005-06-03 12:20     ` Al Viro
2005-06-03 14:19       ` Jörn Engel
2005-06-03 12:28     ` Andreas Schwab
2005-06-03 12:43       ` Geert Uytterhoeven
2005-06-03 14:38         ` Andreas Schwab
2005-06-03 18:04           ` randy_dunlap
2005-06-03 18:09             ` Lars Marowsky-Bree
2005-06-03 18:16               ` randy_dunlap
2005-06-04 11:28             ` Christoph Hellwig
2005-06-04 16:58               ` randy_dunlap
2005-06-04 17:07                 ` Jörn Engel
2005-06-04 17:11                   ` randy_dunlap

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