INITIAL_MEMORY option is broken

[jeffRTC]

I have set INITIAL_MEMORY to 134217728 and then got an error which said that I should set the value to 278505584, but after setting that I got this error,

em++: error: INITIAL_MEMORY must be a multiple of WebAssembly page size (64KiB), was 278505584

Then, I have set it to 33554432, but now I'm getting this error,

wasm-ld: error: initial memory too small, 278505584 bytes needed

[jeffRTC]

As a side note, I do use ALLOW_MEMORY_GROWTH option but to use Sanitizers it still require INITIAL_MEMORY option to be set. This is not the actual behavior according to your docs,

You probably need to increase INITIAL_MEMORY to at least 64 MB **or** pass -s ALLOW_MEMORY_GROWTH so that ASan has enough memory to start

emcc -gsource-map -fsanitize=address -s ALLOW_MEMORY_GROWTH buffer_overflow.c

My CMake settings looks like this,

add_compile_options("SHELL: -s ALLOW_MEMORY_GROWTH=1")
add_link_options("SHELL: -s ALLOW_MEMORY_GROWTH=1")

[jeffRTC]

cc @sbc100 @kripken

[sbc100]

What if you take the value that wasm-ld is requiring (278505584) and round it up to nearest 64k page? Or just round it up to 300Mb for good measure?

Do you know wasm-ld is requiring 278Mb? That seems quite high? IIRC that means you have that much static data in your program? Can you share buffer_overflow.c so we can see why that static data requirements are so high for that file?

[jeffRTC]

@sbc100 buffer_overflow.c is from your docs. I used it as a reference that -s ALLOW_MEMORY_GROWTH should not require INITIAL_MEMORY option but in my case I have to add it because it don't let me to compile.

Do you know wasm-ld is requiring 278Mb?
How to checkthis?

[sbc100]

I see the problem. ALLOW_MEMORY_GROWTH means that the asan shadow memory needs to handle memories as large as MAXIMUM_MEMORY, which by default is 2Gb.

To fix the issue you can either increase your INITIAL_MEMORY (to handle the larger shadow memory size).. or set your MAXIMUM_MEMORY.

Going forward we should probably increase INITIAL_MEMORY automatically when using ASAN (or at least give a better error here).

[jeffRTC]

@sbc100 500 MB fixed the issue for me. So, close?