Before I read your code. Valgrind reporting invalid free error is not because of leaked memory, but you try to free invalid memory (or free same memory more than once). Compiling your code with the compilter flag -g (gdb debug), will enable more debug information, making the backtraces from valgrind much better. A quick guess:
You’re overstepping the array. Either change <= to < or alloc SIZE + 1 elements Your malloc is wrong, you’ll want sizeof(double) instead of sizeof(double *) As ouah comments, although not directly linked to your corruption problem, you’re using *(ptr+tcount) without initializing it Just as a style note, you might want to use ptr[tcount] instead … Read more
OK some answers about malloc were already posted. The more interesting part is how free works (and in this direction, malloc too can be understood better). In many malloc/free implementations, free does normally not return the memory to the operating system (or at least only in rare cases). The reason is that you will get gaps in … Read more
You’re attempting to free something that isn’t a pointer to a “freeable” memory address. Just because something is an address doesn’t mean that you need to or should free it. There are two main types of memory you seem to be confusing – stack memory and heap memory. Stack memory lives in the live span of the function. … Read more
I am doing very basic dynamic allocation practice in C and I came across this issue: when I am trying to call free() with the pointer returned by malloc(), I am getting Invalid pointer error during run time. When I remove free() from code, it works fine. The pointer that I am using is not modified anyhow after returned by malloc (except … Read more
OK, so I’ve managed to overcome this issue. First of all – A practical cause to “corrupted size vs. prev_size” is quite simple – memory chunk control structure fields in the adjacent following chunk are being overwritten due to out-of-bounds access by the code. if you allocate x bytes for pointer p but wind up writing beyond x in regards to … Read more
If you’re using glibc, you can set the MALLOC_CHECK_ environment variable to 2, this will cause glibc to use an error tolerant version of malloc, which will cause your program to abort at the point where the double free is done. You can set this from gdb by using the set environment MALLOC_CHECK_ 2 command before running your program; the program … Read more
When I run my (C++) program it crashes with this error. * glibc detected * ./load: double free or corruption (!prev): 0x0000000000c6ed50 *** How can I track down the error? I tried using print (std::cout) statements, without success. Could gdb make this easier?