Re: Memory corruption (?) I don't understand

[BERTRAND Joël]

        Strange. Following function runs as expected.

enum ldl_mac_status LDL_MAC_otaa(struct ldl_mac *self)
{
    enum ldl_mac_status retval;
    union ldl_mac_response_arg arg;

    LDL_PEDANTIC(self != NULL)

    if(self->ctx.joined){

        retval = LDL_STATUS_JOINED;
    }
    else if(self->op == LDL_OP_NONE){

        if(self->devNonce <= U32(UINT16_MAX)){

            forgetNetwork(self);

            self->trials = 0;

            self->day = U32(60) * U32(60) * U32(24) * timeTPS;

#if defined(LDL_ENABLE_L2_1_1)
            LDL_OPS_deriveJoinKeys(self);
#endif
            fillJoinBuffer(self, U16(self->devNonce));

            self->devNonce++;

            arg.dev_nonce_updated.nextDevNonce = self->devNonce;

unsigned char t[80];
sprintf(t, "self->handler=%p\r\n", self->handler);
            self->handler(self->app, LDL_MAC_DEV_NONCE_UPDATED, &arg);

            self->tx.power = 0;

            self->op = LDL_OP_JOINING;

            if(self->state == LDL_STATE_IDLE){

                self->state = LDL_STATE_WAIT_OTAA;
                LDL_MAC_timerSet(self, LDL_TIMER_WAITA, 0);
            }

            retval = LDL_STATUS_OK;

            LDL_DEBUG("OTAA is pending")
        }
        else{

            /* need to re-init with a different JoinEUI */
            retval = LDL_STATUS_DEVNONCE;
        }
    }
    else{

        retval = LDL_STATUS_BUSY;
    }

    return retval;
}

        If I comment out sprintf(), it crashes. If I deplace this debug trace
before or _after_ self->handler call, firmware runs as expected. I don't
understand. If there is a memory corruption somewhere, I could
understand that a debug trace _before_ the line that triggers the bug
can change something. But I don't understand why the following function
runs as expected :

enum ldl_mac_status LDL_MAC_otaa(struct ldl_mac *self)
{
    enum ldl_mac_status retval;
    union ldl_mac_response_arg arg;

    LDL_PEDANTIC(self != NULL)

    if(self->ctx.joined){

        retval = LDL_STATUS_JOINED;
    }
    else if(self->op == LDL_OP_NONE){

        if(self->devNonce <= U32(UINT16_MAX)){

            forgetNetwork(self);

            self->trials = 0;

            self->day = U32(60) * U32(60) * U32(24) * timeTPS;

#if defined(LDL_ENABLE_L2_1_1)
            LDL_OPS_deriveJoinKeys(self);
#endif
            fillJoinBuffer(self, U16(self->devNonce));

            self->devNonce++;

            arg.dev_nonce_updated.nextDevNonce = self->devNonce;

            self->handler(self->app, LDL_MAC_DEV_NONCE_UPDATED, &arg);

            self->tx.power = 0;

            self->op = LDL_OP_JOINING;

            if(self->state == LDL_STATE_IDLE){

                self->state = LDL_STATE_WAIT_OTAA;
                LDL_MAC_timerSet(self, LDL_TIMER_WAITA, 0);
            }

            retval = LDL_STATUS_OK;

            LDL_DEBUG("OTAA is pending")
        }
        else{

            /* need to re-init with a different JoinEUI */
            retval = LDL_STATUS_DEVNONCE;
        }
    }
    else{

        retval = LDL_STATUS_BUSY;
    }

unsigned char t[80];
sprintf(t, "self->handler=%p\r\n", self->handler);
    return retval;
}

        Of course, if I comment out :

unsigned char t[80];
sprintf(t, "self->handler=%p\r\n", self->handler);

it crashes again :

hilbert:[~/cvs/firmware-antivol] > simavr -t -vvv -m atmega1284 -f
16000000 firmware.elf
Loaded 95670 .text at address 0x0
Loaded 5654 .data
Loaded 2276 .eeprom
01..
..
=================..
 Systella L100-A..
=================..
..
Booting firmware 2021062218..
SPI initialized..
Reset LORA..
Reset LORA done..
LoRaWAN 1.1..
Initialization SX1262..
Initialization SX1262 done..
0000000000000000..
MAC initialization..
LDL_MAC_addChannel:790>chIndex=0 freq=868100000 minRate=0 maxRate=5..
LDL_MAC_addChannel:790>chIndex=1 freq=868300000 minRate=0 maxRate=5..
LDL_MAC_addChannel:790>chIndex=2 freq=868500000 minRate=0 maxRate=5..
cb type=11..
processInit:994>set radio reset: ticks=151..
processRadioReset:1009>clear radio reset: ticks=151..
MAC initialization done..
lora_send..
processStartRadioForEntropy:1061>listen for entropy: ticks=152..
processEntropy:1078>read entropy: ticks=152 entropy=0..
cb type=0..
LDL_MAC_ready..
LDL_MAC_otaa..
LDL_MAC_addChannel:790>chIndex=0 freq=868100000 minRate=0 maxRate=5..
LDL_MAC_addChannel:790>chIndex=1 freq=868300000 minRate=0 maxRate=5..
LDL_MAC_addChannel:790>chIndex=2 freq=868500000 minRate=0 maxRate=5..
avr_gdb_init listening on port 1234