Stack overflow on Attribute write callback thread

Question

I have my software set up so that it does some computation within the Attribute write callback function like this.

static ssize_t KeyInitiation(struct bt_conn *conn, const struct bt_gatt_attr *attr, const void *buf, uint16_t len, uint16_t offset, uint8_t flags)
{


uint8_t kew_vouch[KEY];
uint8_t kew_new[KEY];
uint8_t signature[SIGNATURE];

memcpy(kew_vouch, buf, KEY);
memcpy(kew_new, buf + KEY, KEY);
memcpy(signature, buf + KEY + KEY, SIGNATURE);


#if CONFIG_LOG
LOG_HEXDUMP_DBG(kew_new, KEY, "kew_new");
LOG_HEXDUMP_DBG(kew_vouch, KEY, "kew_vouch");
LOG_HEXDUMP_DBG(signature, SIGNATURE, "signature");
#endif


broadcastKeyHandler(kew_new, kew_vouch, signature);

return len;
}

broadcastKeyHandler does somewhat of a big jobb here. calling broadcastKeyHandler from main does not seem to be a problem. but when called from the attribute, I get this error:

[00:00:13.891,632] <err> os: ***** USAGE FAULT *****
[00:00:13.891,662] <err> os: Stack overflow (context area not valid)
[00:00:13.891,693] <err> os: r0/a1: 0x2003fb70 r1/a2: 0x0000000c r2/a3: 0x00000000
[00:00:13.891,723] <err> os: r3/a4: 0x2003fb2c r12/ip: 0x00000003 r14/lr: 0x00044925
[00:00:13.891,723] <err> os: xpsr: 0x61000200
[00:00:13.891,723] <err> os: Faulting instruction address (r15/pc): 0x00042d40
[00:00:13.891,784] <err> os: >>> ZEPHYR FATAL ERROR 2: Stack overflow on CPU 0
[00:00:13.891,815] <err> os: Current thread: 0x20031348 (unknown)

I think this might because of the stack size delegated to the thread spawned when the attribute is called upon. If that is the case, then how do I increase the stack size of the thread?

SimonDar · Accepted Answer

For anyone else encountering the same issue, setting the variables as static provided a fix. However, I'm uncertain whether this is due to a scope or a thread stack issue. Can anyone advise on how to increase the stack sizes for these threads, assuming they are indeed threads? 
 I suspect that these might be threads because I can still interact with them after implementing k_sleep in the main function. Please correct me if I'm wrong.

Stack overflow on Attribute write callback thread

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