Error read characters of string ,unable to access memory

perseusdg 1

I am trying to copy some buffers i read from buffer to variables in a class,
const char * buf = reinterpret_cast<const char*>(serialData);//buffer

Initializing the constructor
YoloRT *r = new YoloRT(readBUF<int>(buf), //classes
readBUF<int>(buf), //num
nullptr, //yolo
readBUF<int>(buf), //n_masks
readBUF<float>(buf), //scale_xy
readBUF<float>(buf), //nms_thresh
readBUF<int>(buf), //nms_kind
readBUF<int>(buf) //new_coords
);
for (int i = 0; i < r->n_masks; i++)
{
r->mask[i] = readBUF<dnnType>(buf);//error line
}
The error pop ups at the line mentioned, When I debug it, the error statement reads and points at buf and the value of "i" at which this error occurs changes everytime I debug it. I am confused as to what is happening here as the same code works perfectly fine on linux.It would be amazing if someone can explain why this is happening only in windows(MSVC toolchain) and any workarounds for it?

perseusdg 1 Reputation point

2021-02-19T19:20:58.083+00:00

It would really amazing if someone can help me out here, I have been scratching my head over this issue for weeks..the code runs perfectly fine with gcc ,clang and icc in linux but not using MSVC
Viorel 114.7K Reputation points

2021-02-19T19:26:21.043+00:00

Did you check if r->n_masks contains the expected value?
perseusdg 1 Reputation point

2021-02-19T19:56:27.58+00:00

What do you mean contains the expected value exactly? till buf throws out an error r->n_masks contains the expected value
Viorel 114.7K Reputation points

2021-02-19T20:03:57.65+00:00

You have the data (serialData or buf) and you probably know the indices of bytes that contains n_mask. Then you can extract it manually in Debugger. Check if r->n_mask contains the same, correct value.

Also check if other members of r look good. (Maybe compare with the code that runs fine).
perseusdg 1 Reputation point

2021-02-19T21:30:58.793+00:00

Yeah ,r->n_mask and the other members of r look good too till it hits error on reading buf at some i
Viorel 114.7K Reputation points

2021-02-20T08:44:16.077+00:00
Make sure that mask is correctly allocated, containing enough elements to keep n_masks items of dnnType. (Show some code details). Also check if serialData actually includes the source data; maybe it is shorter than expected.

Maybe you can split the body to:

dnnType dnn = readBUF<dnnType>(buf); r->mask[i] = dnn;

Then see which of these two lines does not work.

perseusdg 1

I am allocating my masks correctly in the constructor like this

YoloRT(int classes, int num, tk::dnn::Yolo *yolo = nullptr, int n_masks=3, float scale_xy=1, float nms_thresh=0.45, int nms_kind=0, int new_coords=0) {

    this->classes = classes;
    this->num = num;
    this->n_masks = n_masks;
    this->scaleXY = scale_xy;
    this->nms_thresh = nms_thresh;
    this->nms_kind = nms_kind;
    this->new_coords = new_coords;

    mask = new dnnType[n_masks];
    bias = new dnnType[num*n_masks*2];
    if(yolo != nullptr) {
        memcpy(mask, yolo->mask_h, sizeof(dnnType)*n_masks);
        memcpy(bias, yolo->bias_h, sizeof(dnnType)*num*n_masks*2);
        classesNames = yolo->classesNames;
    }
}

and the error occurs in the first line you wrote

Viorel 114.7K Reputation points

2021-03-08T13:46:16.047+00:00

Maybe buf, i.e. serialData, is smaller and does not include all of dnnType values. Do you know the size of serialData and if it is correctly allocated? Also check the last value of i before the exception.
perseusdg 1 Reputation point

2021-03-08T14:45:16.467+00:00

The last value of i before the exception is never the same, its value changes after every run ,yes i do know the size of serialData but both the size and serialData come from tensorrt(closed source nvidia lib) ,i have no way of checking how its allocated i believe correct me if I am wrong though
perseusdg 1 Reputation point

2021-03-12T15:55:18.657+00:00

So i ran my program with msvc address sanitizers enabled, turns out its a heap overflow error

1 answer

Petrus 【KIM】 456 Reputation points

2021-02-25T01:33:36.53+00:00
The "YoloRT" class should allocate memory for the "mask" menber in the constructor.

YourRT(...... int n_masks ......) { mask = new dnnType[n_masks]; }
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perseusdg 1 Reputation point

2021-03-08T13:03:05.38+00:00

Yeah, my constructor does that ,I have shown my constructor in the comment above
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Error read characters of string ,unable to access memory

1 answer