[gdal-dev] MEM Datasets

[Frank Warmerdam]

James Meyer wrote:
> Hi
> 
> Actually I did call it.
> Sorry I just didn't include it in the code because it was much earlier 
> in the program.
> 
> However after some playing around, it seems that the error only occurs 
> IF I did a write to the MEM dataset. (Although it occurs WHEN I close it).
> 
> The code I am using to test is below line-for-line exact. I basically 
> read from an existing dataset (known to be GDT_Byte) into the in-memory 
> dataset.
> 
> It seems like some sort of buffer overflow, because if I delete the last 
> two lines (that frees the buffers) I get a long "stack smash detected" 
> printout in stead of a segmenation fault.
> 
> Can you see anything I am doing wrong?
...
>>      void* data = malloc(datasize);
>>      sprintf(filename,
>>        "MEM:::DATAPOINTER=%p,PIXELS=%d,LINES=%d,BANDS=%d,DATATYPE=%s",
>>     &data, 100, 100, 1, GDALGetDataTypeName(GDT_Byte));

James,

In the sprintf() you should be passing "data" instead of "&data".  Currently
you are passing the pointer to the pointer "data" on the stack which is only
4-8 bytes long and that is being used, and written past, blowing the stack.

Best regards,
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