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SubjectRe: [PATCH] mm/sl[aou]b: make kfree() aware of error pointers
On Wed, 10 Sep 2014, Andrey Ryabinin wrote:

> > I of course have no objections to this check being added to whatever
> > static checker, that would be very welcome improvement.
> >
> > Still, I believe that kernel shouldn't be just ignoring kfree(ERR_PTR)
> > happening. Would something like the below be more acceptable?
> >
> >
> >
> > From: Jiri Kosina <jkosina@suse.cz>
> > Subject: [PATCH] mm/sl[aou]b: make kfree() aware of error pointers
> >
> > Freeing if ERR_PTR is not covered by ZERO_OR_NULL_PTR() check already
> > present in kfree(), but it happens in the wild and has disastrous effects.
> >
> > Issue a warning and don't proceed trying to free the memory if
> > CONFIG_DEBUG_SLAB is set.
> >
>
> This won't work cause CONFIG_DEBUG_SLAB is only for CONFIG_SLAB=y
>
> How about just VM_BUG_ON(IS_ERR(ptr)); ?

VM_BUG_ON() makes very little sense to me, as we are going to oops anyway
later, so it's a lose-lose situation.

VM_WARN_ON() + return seems like much more reasonable choice.

--
Jiri Kosina
SUSE Labs


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