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Date: Tue, 25 Jun 2019 09:46:39 -0400
From: Alex Gaynor <>
Subject: Re: Thousands of vulnerabilities, almost no CVEs: OSS-Fuzz

20% was a completely made us number.


On Tue, Jun 25, 2019, 9:42 AM Bob Friesenhahn <>

> On Mon, 24 Jun 2019, Alex Gaynor wrote:
> > - Not having sooooo many vulnerabilities. While there's some dispute over
> > just what % of the bugs that OSS-Fuzz and syzbot turn up are exploitable,
> > there's no doubt that they find a _lot_ of them. Even if only 20% of
> > OSS-Fuzz reports were truly exploitable vulnerabilities, that'd still be
> >> 600 of them. We can't produce this many vulnerabilities and then try to
> > clean up afterwards by finding them with fuzzing -- at some point the
> > number of vulnerabilities simply overwhelms us. Tactics for reducing
> > vulnerabilities in the first instance, like memory safe languages, are an
> > important part of making this problem tractable.
> >
> > Do folks feel like there were important themes that this misses?
> I see the assumption that 20% of oss-fuzz reports are exploitable
> vulnerabilities.  Where does this percentage estimate come from?  What
> does it mean to be "exploitable"?
> From working on fixing oss-fuzz detected bugs in GraphicsMagick I see
> that many/most of the issues are not significant from a security
> standpoint, assuming that the software is deployed in a way suitable
> for its level of exposure.  Common issues include:
>   * Huge uninitialized memory allocations (which do not really matter
>     under Linux since Linux does not reserve anything but virtual
>     memory space).
>   * Consumption of uninitialized data (e.g. image data) which is not
>     used to make important decisions.  This is usually due to unhandled
>     cases or error handling which does not quit immediately.
>   * Tiny heap over-reads which are not past the bounds of the
>     underlying allocation.
>   * Heap over-reads or over-writes which cause an immediate core dump.
>   * Excessively slow code with the slowness emphasized by ASAN and
>     UBSAN code running vastly slower.  The excessively slow code is not
>     necessarily noticeable in a normal compilation.
>   * Memory leaks.
>   * "undefined behavior" which nevertheless has a common behavior that
>     compilers have followed since the dawn of time.
> The most important thing that oss-fuzz contributes is a large
> collection of files which cause problems for unfixed software such
> that only the unaware or foolish do not update to fixed versions.
> Bob
> --
> Bob Friesenhahn
> GraphicsMagick Maintainer,
> Public Key,

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