KW40Z HardFault in hciLeCallback

bpratt — Mon, 06 Mar 2017 17:40:48 GMT

Hello,

I am using the KW40Z in the GAP Central role to scan and connect to other BLE devices. Occasionally, a HardFault will be triggered while processing scan requests. I've managed to trace the issue back to a potential null-pointer dereference in "hciLeCallback" from "gap_hci_cb.o" in "ble_host_central_lib.a" within Connectivity Software 1.0.1.

The disassembly for this function is shown below. There is a conditional breakpoint on address 0x1875C right after the call to "MEM_BufferAlloc". Notice that there is no check to verify that "MEM_BufferAlloc" did not return NULL, unlike the previous call to "MEM_BufferAlloc" earlier in the function (starting at address 0x18736, the "MOVS" followed by the "BEQ.N").

Ultimately, the HardFault occurs within the call to "FLib_MemCpy" at address 0x1877C where we end up trying to write to address 0. A snapshot of this condition is shown below (destination in R0, source in R1). There are a few reads and writes that occur between the call to "MEM_BufferAlloc" and "FLib_MemCpy" that I haven't fully decoded, but they don't seem to help us avoid writing to address 0.

I suspect I can increase the heap size to avoid running into this situation, but it doesn't fix the underlying cause. Is there a planned update to the Connectivity Software that happens to address this issue?

Thanks,

Ben

Re: KW40Z HardFault in hciLeCallback

jorge_a_vazquez — Mon, 27 Mar 2017 18:57:41 GMT

Hi Ben Pratt

Thanks for your feedback, I will verify this information and tell to the people that take care of this. Your issue seams to be a improvement, so it should be in the next release, but it may take time to be released.

Best Regards

Jorge Alcala

Re: KW40Z HardFault in hciLeCallback

bpratt — Tue, 04 Apr 2017 17:11:32 GMT

Hi Jorge,

Thanks for the acknowledgement. Increasing the heap size did allow us to avoid the situation. Looking forward to the next release.

Thanks,

Ben

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