String parsing failes when using a function doing substring in C - c

Question

I am having an issue with parsing a string in C. It causes a HardFault eventually.
MCU: LPC1769,
OS: FreeRTOS 10,
Toolchain: IAR
In order to test, If I keep sending the same data frame (you may see the sample below in message variable in parseMessage function),
after 5-6 times parsing it goes OK, parsing works as I expected, and then suddenly falls in HardFault when I send one more the exact same string to the function.
I tested the function in OnlineGDB. I haven't observed any issue.
I have couple of slightly different version of that function below although the result is the same;
char *substr3(char const *input, size_t start, size_t len) {
char *ret = malloc(len+1);
memcpy(ret, input+start, len);
ret[len] = '\0';
return ret;
}
I've extracted the function piece for a better overveiw:
(don't pay attention to stripEOL(message); call, it just strips out end-of-line characters, but you can see it in the gdbonline share of mine)
void parseMessage(char * message){
//char* message= "7E00002A347C31323030302D3132353330387C33302E30372E323032307C31317C33307C33317C31352D31367C31357C317C57656E67657274880D";
// Parsing the frame
char* start;
char* len;
char* cmd;
char* data;
char* chksum;
char* end;
stripEOL(message);
unsigned int messagelen = strlen(message);
start = substr3(message, 0, 2);
len = substr3(message, 2, 4);
cmd = substr3(message, 6, 2);
data = substr3(message, 8, messagelen-8-4);
chksum = substr3(message, messagelen-4, 2);
end = substr3(message, messagelen-2, 2);
}
Only the data variable differs in length.
e.g. data --> "347C31323030302D3132353330387C33302E30372E323032307C31317C33307C33317C31352D31367C31357C317C57656E67657274"
A HardFault debug log:
LR = 0x8667 in disassembly
PC = 0x2dd0 in disassembly

Answer 1

I appreciate to the contributors which they led me to find the solution for my instance.
Since there wasn't a total solution by the contributors and I found a working solution, I'd better be writing for whom may interest in future.
Since I am developing my application on top of FreeRTOS 10 and using malloc from the C library, apparently it wasn't cooping at least with my implementations. It's been said in some resources, you can use standard malloc within FreeRTOS, I couldn't manage myself for some unknown reason. It might have been a help, if I had increased the heap memory, I don't know but I didn't have intention on that as well.
I've just placed that two wrapper functions (somewhere in a common file) without even changing my malloc and free calls.;
Creating a malloc/free functions that work with the built-in FreeRTOS heap is quite simple. We just wrap the pvPortMalloc/pvPortFree calls:
void* malloc(size_t size)
{
void* ptr = NULL;
if(size > 0)
{
// We simply wrap the FreeRTOS call into a standard form
ptr = pvPortMalloc(size);
} // else NULL if there was an error
return ptr;
}
void free(void* ptr)
{
if(ptr)
{
// We simply wrap the FreeRTOS call into a standard form
vPortFree(ptr);
}
}
Note that: You can't use that with heap schema #1 but with the others (2, 3, 4 and 5).
I would recommend start using portable/MemMang/heap_4.c