On Thu, Jul 26, 2012 at 9:14 AM, Geoffrey Irving <irv...@naml.us> wrote:
> I'm using valgrind 3.8.0.SVN from MacPorts on Mac OS X 10.7.4.
> valgrind is showing a memory leak of 18 bytes when I try to allocate
> an empty array using posix_memalign. The leak warning is attached.
>
> The posix_memalign call is
>
> void* data;
> const size_t alignment = max(sizeof(T),sizeof(void*));
> if (posix_memalign(&data,alignment,sizeof(T)*size))
> throw bad_alloc();
>
> where sizeof(T)==64 and size==0. I've confirmed that I call free on
> the same pointer. If I replace the code with
>
> void* data = malloc(sizeof(T)*size);
>
> the leak warning goes away. Any idea what could be going wrong?
Okay, this looks like a bug in Mac's posix_memalign, not a valgrind
issue. Here's a reduced test program:
#include <stdlib.h>
#include <stdio.h>
int main() {
void* data = 0;
int r = posix_memalign(&data,64,0);
printf("r = %d, data = %p\n",r,data);
free(data);
return 0;
}
Running this produces
tile:scratch% ./memalign
r = 0, data = 0x106900840
memalign(3949) malloc: *** error for object 0x106900840: pointer
being freed was not allocated
*** set a breakpoint in malloc_error_break to debug
Abort trap: 6
Allocating 64 bytes instead of 0 works fine. I'll tell Apple about it
and add the !size check to my code.
Thanks,
Geoffrey
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