SEGV in _cjose_jws_build_hdr when using custom alloc

[zachmann]

When setting a custom memory allocator and deallocator using

cjose/src/util.c

Line 60 in 9261231

void cjose_set_alloc_funcs(cjose_alloc_fn_t alloc, cjose_realloc_fn_t realloc, cjose_dealloc_fn_t dealloc)

it is also applied to json.
In

cjose/src/jws.c

Lines 54 to 65 in 254ab05

	char *hdr_str = json_dumps(jws->hdr, JSON_ENCODE_ANY | JSON_PRESERVE_ORDER);
	if (NULL == hdr_str)
	{
	CJOSE_ERROR(err, CJOSE_ERR_NO_MEMORY);
	return false;
	}
	if (!cjose_base64url_encode((const uint8_t *)hdr_str, strlen(hdr_str), &jws->hdr_b64u, &jws->hdr_b64u_len, err))
	{
	free(hdr_str);
	return false;
	}
	free(hdr_str);

json_dumps allocatos hdr_str using the custom allocator. However later hdr_str is freed using free and not the set deallocator. So this (can) lead to a segfault.

I suggest to replace the calls to free with cjose_get_dealloc()

[zandbelt]

this was merged here:
OpenIDC#7
and now part of the maintenance fork here:
https://github.com/OpenIDC/cjose/tree/version-0.6.2.x