problem with malloc

Hi

I'm trying to execute some C++ code on an LPC1768, an ARM Cortex-M3 driven microcontroller.
The C++ code uses malloc and free, so I included <stdlib.h>. While building and compiling the code with arm-none-eabi-gcc gave no errors, the binary does not execute. The Cortex-M3 goes into HardFault.

When compiling the exact same code with the online compiler of mbed (https://developer.mbed.org/compiler/) the binary does execute!

This leads me to believe that my compilation process, when I use arm-none-eabi-gcc, is not correct. Could it be that the wrong <stdlib.h> and thus the wrong implementation of malloc() and free() are included into the binary, causing the hardfault?

here are the contents of the makefile:

--> dijkstra.cpp includes the code that calls malloc() and free()
$(cpp) -I(...) dijkstra.cpp -o algorithms/dijkstra.o

--> linker to create the elf (the binary is extracted from the .elf )
$(cpp) -T"lpc1768.ld" -nostartfiles -Xlinker --gc-sections -WL,-Map,"dijkstra.map" --specs=nosys.specs ..... -o dijkstra.elf

Could you please let me know what I do wrong?

Thanks in advance.