Re: [PATCH 7/16] Let void have sizeof 1

[Derek M Jones <derek@knosof.co.uk>]

Alexey,

I have been looking through the source to look at the contexts
in which arithmetic is performed on void pointers.

>>   1) Are the arguments really chars of one sort or another and
>> therefore the parameter ought to be declared as such?
> You mean, if address arithmetics is performed on a void * cast result,
> check that the casted type too has sizeof 1?

I was thinking more along the lines of pointer to a character type being
converted to void * for no obvious reason, or a value being converted to
void * having an arithmetic operation performed and then converted to
a pointer to character type.
For an example see line 156 of arch/x86/kernel/module_64.c

I would expect the void * to come from/go to a type that had a
size greater than 1.

>>   4) Other possible fault issues, people?

I have found an instance (arch/x86/kernel/kprobes.c:834) that
effectively does:

(void *)long_val + an_int_calculation

when it should have done:

(void *)(long_val + an_int_calculation)

hardly an earth shattering misuse.

-- 
Derek M. Jones                         tel: +44 (0) 1252 520 667
Knowledge Software Ltd                 mailto:derek@knosof.co.uk
Source code analysis                   http://www.knosof.co.uk