Date: Tue, 25 Jun 2019 08:41:08 -0500 (CDT) From: Bob Friesenhahn <bfriesen@...ple.dallas.tx.us> To: oss-security@...ts.openwall.com Subject: Re: Thousands of vulnerabilities, almost no CVEs: OSS-Fuzz 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 bfriesen@...ple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/ GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ Public Key, http://www.simplesystems.org/users/bfriesen/public-key.txt
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