Re: LLVM Address Sanitizer (ASAN) and valgrind support

From: Greg Stark <stark(at)mit(dot)edu>
To: Noah Misch <noah(at)leadboat(dot)com>
Cc: PostgreSQL-development <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: LLVM Address Sanitizer (ASAN) and valgrind support
Date: 2016-10-19 10:08:39
Message-ID: CAM-w4HObfQVs=JqcEx3-04g8gXnO4DU6AJNYgczqytSL6PALQA@mail.gmail.com
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On Sat, Feb 6, 2016 at 4:52 AM, Noah Misch <noah(at)leadboat(dot)com> wrote:
> aset.c relies on the fact that VALGRIND_MEMPOOL_ALLOC() has an implicit
> VALGRIND_MAKE_MEM_UNDEFINED() and VALGRIND_MEMPOOL_FREE() has an implicit
> VALGRIND_MAKE_MEM_NOACCESS(). #define those two accordingly. If ASAN has no

Actually this is confusing.

aset.c doesn't actually use the MEMPOOL_ALLOC macro at all, it just
calls UNDEFINED, DEFINED, and NOACCESS. mcxt.c does however do the
MEMPOOL_ALLOC/FREE. So both layers are calling these macros for
overlapping memory areas which I find very confusing and I'm not sure
what the net effect is.

The MEMPOOL_FREE doesn't take any size argument and mcxt.c doesn't
have convenient access to a size argument. It could call the
GetChunkSpace method but that will include the allocation overhead and
in any case isn't this memory already marked noaccess by aset.c?

--
greg

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