What is the fixed address range you are using?

There are two fixed address ranges that asan is using: one for the shadow,
one for the allocator.

If you are using the latest clang, you may try -mllvm
-asan-force-dynamic-shadow=1, which will make asan use dynamic shadow base.
Note:
  * you can not mix object files built with
asan+asan-force-dynamic-shadow=1 and with asan+asan-force-dynamic-shadow=0
  * this flag is expected to work, but does not have the same amount of
testing as the default mode. So, if something breaks, we may not be able to
help.

I don't think we support dynamic allocator range on x86_64 linux.

It might still be simpler to modify your code to use a range that doesn't
conflict with asan.

--kcc



On Thu, Feb 28, 2019 at 1:32 AM Jason Newton <[email protected]> wrote:

> Hello,
>
> I'm a long time fan/user of asan.  I was trying to use it in an
> application with a big chunk of virtual memory mapped to a fixed address
> range, it's only a fraction of the virtual address space (a significant
> one), but there's still plenty of bits to go around, and hopefully enough
> for asan to do it's thing.
>
> So I was trying to figure out how make asan coexist with this.  asan loads
> up first which then causes problems for the application after that.
> Looking at asan_allocator.h, I can see this:
>
>
> #else //From what I can tell a standard x86_64 intel machine on linux
> should land here.
>
> const uptr kAllocatorSpace = 0x600000000000ULL;
> const uptr kAllocatorSize = 0x40000000000ULL; // 4T.
> typedef DefaultSizeClassMap SizeClassMap;
> # endif
> template <typename AddressSpaceViewTy>
> struct AP64 { // Allocator64 parameters. Deliberately using a short name.
> static const uptr kSpaceBeg = kAllocatorSpace;
>
> static const uptr kSpaceSize = kAllocatorSize;
>
>
> Not quite sure if these are the knobs I'm looking for -  or what the exact
> meaning is of kSpaceBeg/kAllocatorSpace
> Basically my thought is , could I restrict libasan so it only claims the
> virtual address space above the problematic region.
>
> Thoughts or pointers?
>
> -Jason
>
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