malloc causing fault in SoftDevice

RE: malloc causing fault in SoftDevice

Jørgen Holmefjord — Tue, 14 Mar 2023 13:08:29 GMT

Looks like you have ended up in the error handler, which would typically happen if a function returns an error. Please create a new ticket where you describe your problem and we will help you resolve it.

RE: malloc causing fault in SoftDevice

Sebastien DRI — Wed, 08 Mar 2023 14:41:13 GMT

Hi Folks,

Any fix concerning this issue cause we are facing the same problem randomly at the same address offset (See Screeshot below).

As you can see, it is located at 0x1505C and a fault ID of 1 (and info of 0) and the instruction refers to a call to "svc 255" (supervisor call but unknow id).

I use SDK 16.0.0 with softdevice 7.0.1

I must add that this error occurs randomly in our functionning more precisely when uploading data to the target (which is a peripheral configured in long range mode) from a central so communication is stressed a bit.

RE: malloc causing fault in SoftDevice

Benjamin — Sat, 28 Mar 2020 10:18:15 GMT

I figured out the root cause of these hard faults, but I'm at a loss to explain why they were causing an assertion error in the softdevice.

My application takes variable length commands via usb serial and parses (application-level) headers before reading more data based on the headers. There's a state variable that keeps track of what's been parsed and I had missed a state transition. This lead to payload data shifted further into the input buffer by the length of a header. This wouldn't cause any overflow, because the input buffer is much larger than these particular messages.

The part that perplexes me is that nothing was interacting with that corrupt data, aside from copying it to a temporary buffer, and then writing it to flash. In the struct for that data, the values are just numbers. If they were being used as a pointer, I could see how that could lead to errors by trying to access unavailable memory, but that wasn't the case here.

The only other thing I can think of is data languishing in the CDC ACM internal 'in' buffer, but all of this code was ultimately being called from the same `cdc_acm_user_evt_handler`.

RE: malloc causing fault in SoftDevice

Benjamin — Sat, 28 Mar 2020 01:58:42 GMT

And I spoke too soon, because the issue is back, but only the 2nd time the function is called via that particular code path. The same function is called via a different code path (during init) repeatedly without issue.

Also, the error consistently occurs on this codepath if I'm stepping through w/ a debugger.

RE: malloc causing fault in SoftDevice

Benjamin — Sat, 28 Mar 2020 01:07:10 GMT

Some unrelated bug-fixing has caused this problem to miraculously fix itself.

Our best guess is the softdevice somehow got corrupted and various subsequent wipes & re-flashes solved the issue.

RE: malloc causing fault in SoftDevice

Benjamin — Fri, 27 Mar 2020 21:15:39 GMT

I'm using the SDK v16 with the s140. I'm very loosely basing this on the flash_fds example.

My code is building an in-memory index of what's being stored via FDS. The actual call is:

pattern_index_t volatile *node = malloc(sizeof(pattern_index_t));

where

typedef volatile struct pattern_index_t {
    struct pattern_index_t volatile *p, *n;
    uint16_t record_key;
    uint32_t record_id;
    pattern_t *p_pattern;
} pattern_index_t;

It's part of a function that builds an index node after `fds_record_write_reserved` returns successfully.

If I break out `sizeof(pattern_index_t)` into its own variable, I still get the error.

I should also add I am calling malloc (& calloc) a couple other places successfully.

RE: malloc causing fault in SoftDevice

Jørgen Holmefjord — Fri, 27 Mar 2020 12:00:59 GMT

Hi,

Which SDK and softdevice version are you using? Are you basing this on an SDK example?

Can you post a code snippet of how you use malloc?

Best regards,
Jørgen