Re: [PATCH v5 16/16] reftable: be more paranoid about 0-length memcpy calls

>>> @@ -569,7 +572,8 @@ static int reftable_obj_record_decode(void *rec, struct strbuf key,
>>>  	uint64_t last;
>>>  	int j;
>>>  	r->hash_prefix = reftable_malloc(key.len);
>>> -	memcpy(r->hash_prefix, key.buf, key.len);
>>> +	if (key.len)
>>> +		memcpy(r->hash_prefix, key.buf, key.len);
>>>  	r->hash_prefix_len = key.len;
>>>
>>>  	if (val_type == 0) {
>>
>> I am not sure why any of these are needed.
>> ...
> I don't know about the first two, but in the third case dst (i.e.
> r->hash_prefix) might be NULL if key.len == 0, reftable_malloc is malloc
> (which it is, because reftable_set_alloc is never called) and malloc(0)
> returns NULL (which it might do according to
> https://www.man7.org/linux/man-pages/man3/malloc.3.html).
>
> malloc can return NULL on failure, too, of course, and none of the
> reftable_malloc callers check for that.  That seems a bit too
> optimistic.