Date: Wed, 17 Feb 2016 22:03:59 -0500 From: Daniel Micay <danielmicay@...il.com> To: oss-security@...ts.openwall.com Subject: Re: Address Sanitizer local root On Wed, 2016-02-17 at 17:24 -0800, Konstantin Serebryany wrote: > Sadly MPX is too slow, too memory-hungry, and does not protect from > use-after-free at all. MPX is definitely problematic (performance, memory usage, false positives with some atomic data structures, false positives without using it everywhere - essentially a new ABI) but I don't think the lack of coverage for lifetime issues is a major issue. The malloc implementation can do a good job at mitigating lifetime issues though. It can't detect 100% of UAF issues, but it can force usage of pointers to fault (via proper junk filling) and detect write after free via a comparable quarantine technique + validating that the junk data is unaltered when allocations leave the quarantine. It can be just as good at detecting double-free. See the follow-up email: http://www.openwall.com/lists/oss-security/2016/02/18/3 It's extremely painful to actually debug the aborts and faults produced from this kind of hardening, so it doesn't really displace ASan at all even for the bits where it can be as reliable, and it doesn't cover the read-after-free case in the same way. Download attachment "signature.asc" of type "application/pgp-signature" (820 bytes)
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