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SubjectRe: [PATCH] mm/sl[aou]b: make kfree() aware of error pointers
On Wed, Sep 10, 2014 at 09:56:49AM -0400, Theodore Ts'o wrote:

> The ironic thing is that I asked Dan to add the feature to smatch
> because I found two such bugs in ext4, and I suspected there would be
> more. Sure enough, it found four more such bugs, including two in a
> recent commit where I had found the first two bugs --- and I had
> missed the other two even though I was specifically looking for such
> instances. Oops. :-)
>
> Maybe we can add a debugging config option? I think having static
> checkers plus some kmalloc failure testing should be sufficient to
> prevent these sorts of problem from showing up.
>
> It would seem to me that this is the sort of thing that a static
> checker should find reliably; Coverity has found things that were more
> complex than what this should require, I think. I don't know if they
> would be willing to add something this kernel-specific, though. (I've
> added Dave Jones to the thread since he's been working a lot with
> Coverity; Dave, what do you think?)

It *might* be possible to rig up something using their modelling
functionality, but I've not managed to make that work to my ends in the past.

I suspect a runtime check would be more fruitful faster than they could
implement kernel specific checkers & roll them out.

Dave



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