Uncaught TypeError: Cannot read properties of undefined (reading 'length')

[Flyingbeanss]

Hi! I want to deal with memory access out of bound in my program. After I add set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fsanitize=address") and set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -fsanitize=address") , the console print as follow:

Uncaught TypeError: Cannot read properties of undefined (reading 'length')
    at lengthBytesUTF8 (occt-webgl-sample.js?t=1700141293680:1746:26)
    at stringToNewUTF8 (occt-webgl-sample.js?t=1700141293680:5971:13)
    at occt-webgl-sample.js?t=1700141293680:10523:32
    at withBuiltinMalloc (occt-webgl-sample.js?t=1700141293680:5962:10)
    at _emscripten_pc_get_file (occt-webgl-sample.js?t=1700141293680:10519:37)
    at occt-webgl-sample.wasm.__sanitizer::EmscriptenSymbolizerTool::SymbolizePC(unsigned long, __sanitizer::SymbolizedStack*) (occt-webgl-sample.wasm:0x16a5673)
    at occt-webgl-sample.wasm.__sanitizer::Symbolizer::SymbolizePC(unsigned long) (occt-webgl-sample.wasm:0x16a5960)
    at occt-webgl-sample.wasm.__lsan::LeakSuppressionContext::GetSuppressionForAddr(unsigned long) (occt-webgl-sample.wasm:0x1696920)
    at occt-webgl-sample.wasm.__lsan::LeakSuppressionContext::Suppress(unsigned int, unsigned long, unsigned long) (occt-webgl-sample.wasm:0x1696a6b)
    at occt-webgl-sample.wasm.__lsan::LeakReport::ApplySuppressions() (occt-webgl-sample.wasm:0x1697c0f)

I just don't understand why. Here is the original output.

occt-webgl-sample.js?t=1700142325331:14608 Uncaught RuntimeError: memory access out of bounds
    at occt-webgl-sample.wasm.math_FunctionSetRoot::math_FunctionSetRoot(math_FunctionSetWithDerivatives&, math_Vector const&, int) (occt-webgl-sample.wasm:0xa28b01)
    at invoke_iiiii (occt-webgl-sample.js?t=1700142325331:14605:36)
    at occt-webgl-sample.wasm.math_FunctionRoot::math_FunctionRoot(math_FunctionWithDerivative&, double, double, double, double, int) (occt-webgl-sample.wasm:0xa261a0)
    at occt-webgl-sample.wasm.Extrema_LocEPCOfLocateExtPC::Perform(gp_Pnt const&, double) (occt-webgl-sample.wasm:0x8a659a)
    at invoke_viid (occt-webgl-sample.js?t=1700142325331:14990:29)
    at occt-webgl-sample.wasm.Extrema_LocateExtPC::Perform(gp_Pnt const&, double) (occt-webgl-sample.wasm:0x8a56ff)
    at invoke_viid (occt-webgl-sample.js?t=1700142325331:14990:29)
    at occt-webgl-sample.wasm.Extrema_LocateExtPC::Extrema_LocateExtPC(gp_Pnt const&, Adaptor3d_Curve const&, double, double, double, double) (occt-webgl-sample.wasm:0x8a62af)
    at invoke_iiiidddd (occt-webgl-sample.js?t=1700142325331:16343:36)
    at occt-webgl-sample.wasm.ShapeAnalysis_Curve::ProjectAct(Adaptor3d_Curve const&, gp_Pnt const&, double, gp_Pnt&, double&) const (occt-webgl-sample.wasm:0x4957fd)

Thanks for help , sincerely!

[sbc100]

Hmm.. it looks like convertPCtoSourceLocation must be returning a result that doesn't have a .file attribute so undefined is being passed to stringToNewUTF8 here: https://github.com/emscripten-core/emscripten/blob/9429b4893c5e376e23e67d7007d2b948987445a0/src/library.js#L2819

Strange that we have never seen this before.

Can you try adding -g and/or --profiling-funcs to your compile and link flags?

[Flyingbeanss]

@sbc100 Thanks for reply. Actually, I have added set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -g") and set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -g"). After I add set(CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} --profiling-funcs") and set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} --profiling-funcs"), it seems to be no change in the console.

[sbc100]

Can you take look devtools a few levels up the stack in emscripten_pc_get_file? Can you see what result contains? (The thing that convertPCtoSourceLocation returns?)

[Flyingbeanss]

@sbc100 Thanks for your advice. I'm not very familiar with js and browser.

 var result = convertPCtoSourceLocation(pc);
 if (!result) return 0;

convertPCtoSourceLocation(pc); returns null

[sbc100]

When the crash happens though I'm pretty such it doesn't return null, since it does not return there but goes on to call stringToNewUTF8 below. You need to somehow pause/break when the exceptions happens. Try "Pause on exceptions" in devtools.

Then select the emscripten_pc_get_file and type result in the console to see its contents (or inspect it using the Locals pane).

[Flyingbeanss]

Thank you for being so patient.I make a mistake, it's not null. The convertPCtoSourceLocation(pc); will be called many times.After a certain call, it returns undefined.The content is here: