Re: Suggestion on "int len" sanity

[Willy Tarreau <willy@w.ods.org>]

On Wed, Jun 01, 2005 at 09:06:33AM +0200, XIAO Gang wrote:
> 
> 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?

Probably true for most cases, but be careful of code which would use
-1 to report some errors if such thing exists.

Willy

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