my code can run well, but when I check it with valgrind,there is a error " is 0 bytes after a " - valgrind

Question

here is my code （ Mask_makeMask function） :
unsigned char *Mask_makeMask(int width, unsigned char *frame,
int *mask, HXecLevel level,int version,int autoMask)
{
unsigned char *masked;
unsigned char *tempmask;
int temp;
int maskv[4];
int maskval = *mask;
if(autoMask == 1)
{
tempmask = (unsigned char *)malloc(width * width);
if(tempmask == NULL) return NULL;
//>>>>>mask 00 process Mask_evaluate is to generate the marsk
maskv[0] = Mask_evaluate(width,frame);
//mask 01
maskMakers[0](width, frame, tempmask);
maskv[1] = Mask_evaluate(width,tempmask);
//mask 02
memset(tempmask,0,sizeof(tempmask));
maskMakers[1](width, frame, tempmask);
maskv[2]= Mask_evaluate(width,tempmask);
//mask 03
memset(tempmask,0,sizeof(tempmask));
maskMakers[2](width, frame, tempmask);
maskv[3] = Mask_evaluate(width,tempmask);
temp = maskv[0];
maskval = 0;
int i;
for(i= 1 ;i<4;i++)
{
if(temp >= maskv[i])
{
maskval = i;
temp = maskv[i];
}
}
}
else
{
tempmask = (unsigned char *)malloc(width * width);
if(tempmask == NULL) return NULL;
if(maskval ==0)
Mask_evaluate(width,frame);
else if( maskval >0 && maskval <=3)
{
maskMakers[maskval-1](width, frame, tempmask);
Mask_evaluate(width,tempmask);
}
free(tempmask);
}
>masked = (unsigned char *)malloc(width * width);#line 4319 valgrind
shows this is an error
>if(masked == NULL)
>{
> return NULL;
>}
if(maskval ==0 )
{
memcpy(masked,frame,width * width);
}
else
maskMakers[maskval-1](width, frame, masked);
Mask_writeInformation(width, masked, maskval, level,version);
*mask = maskval;
if(autoMask == 1)
free(tempmask);
return masked;
}
-------my code runs well but the valgrind log is blew:
==2570== Address 0x5c30429 is 0 bytes after a block of size 729 alloc'd
==2570== at 0x4024F20: malloc (vg_replace_malloc.c:236)
>==2570== by 0x410CB07: Mask_makeMask (barhanxin.c:4319)
==2570== by 0x410CF00: HXcode_encodeMask (barhanxin.c:4468)
1. I tried to initialize the masked by using memset(masked,0,width * width)
when the masked is not null, the HXcode_encodeMask called the
Mask_makeMask function,so I think the issue is Mask_makeMask, could anybody
give me some advice how to solve this issue?