Malloc returns NULL Pointer in FreeRTOS task.

[FedeRico1]

Hello Community,

I'm using an ST Nucleo-F767ZI and I create my project, for Atollic True Studio, with Cube32MX.

In my project I included FreeRTOS v10.

I'm in troubled with the malloc function, because this function return a NULL pointer.

I have several tasks, and I'm not able to allocate memory inside a task.

If I invoke the malloc function in the main.c, the function returns a pointer.

I don't know why this happens.

Thanks for the help.

Federico

[JB2500]

I've just tried creating an STM32F767VI FreeRTOS project with the STM32CubeMX in STM32CubeIDE (V1.0.2) rather than the standalone STM32CubeMX (V5.3.0). With this project the offending _sbrk function is in sysmem.c instead of syscalls.c.

Memory allocation in FreeRTOS tasks still fails with this function as is, and works with it renamed / deleted.

I still don't know whether the default _sbrk function (the one that gets used if the sysmem.c / syscalls.c one is renamed / deleted) along with heap_4.c is satisfactory, or whether a solution such as Dave Nadler's one (heap_useNewlib.c) is required.

ST, please advise.

[Pavel A.]

Thank you, very useful info.

> I don't understand why the "<_sbrk>" is in such a bizarre place.

This looks like just an artifact of disassembly.

-- pa

[Sudeep Chandrasekar]

Seems like the exact issue. This saved us lot of time.

[Dave Nadler]

If you expect malloc to work with FreeRTOS, use the code and options described on my web page:

http://www.nadler.com/embedded/newlibAndFreeRTOS.html

[FMagr.1]

Hi guys,

Maybe it can help someone with the same issue.

Just using

pvPortMalloc(size);

and

vPortFree(ptr);

works inside a thread with Heap 4 scheme.

Please read more at https://embeddedartistry.com/blog/2018/01/15/implementing-malloc-with-freertos/ .

Thank you.