On Thu, 2006-12-28 at 09:54 +0100, Jan Engelhardt wrote:
> On Dec 27 2006 17:10, Pavel Machek wrote:
>
> >> Was just wondering if the _var_ in kfree(_var_) could be set to
> >> NULL after its freed. It may solve the problem of accessing some
> >> freed memory as the kernel will crash since _var_ was set to NULL.
> >>
> >> Does this make sense? If yes, then how about renaming kfree to
> >> something else and providing a kfree macro that would do the
> >> following:
> >>
> >> #define kfree(x) do { \
> >> new_kfree(x); \
> >> x = NULL; \
> >> } while(0)
> >>
> >> There might be other better ways too.
---- snip ----
(x) = NULL; \
---- snip ----
?
> >No, that would be very confusing. Otoh having
> >KFREE() do kfree() and assignment might be acceptable.
>
> What about setting x to some poison value from <linux/poison.h>?
That depends on the decision/definition if (so called) "double free" is
an error or not (and "free(NULL)" must work in POSIX-compliant
environments).
Personally I think it is pointless to disallow "kfree(NULL)" by using
some poison value and force people to add a "we have to free that
variable" variable to work around it instead of keeping it NULL (which
makes the "kfree($variable)" a no-op).
Former discussions are to be found in the archives ......
Bernd
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