teec: do fail on MAX_SIZE allocation requests

The variable aligned_sz will be 0 when the requested sz is MAX_SIZE.
Since posix_memalign can return a valid pointer for zero size
allocations, share memory registration requests for MAX_SIZE might make
it to the kernel.

This PR stops it early - just as it was before "teec: use multiple of
page size for page aligned buffers" was merged.

Fixes: acb0885 ("teec: use multiple of page size for page aligned buffers")
Signed-off-by: Jorge Ramirez-Ortiz <jorge@foundries.io>
Reviewed-by: Jens Wiklander <jens.wiklander@linaro.org>

libteec/src/tee_client_api.c

@@ -82,7 +82,7 @@ static void *teec_paged_aligned_alloc(size_t sz)
 	size_t page_sz = sysconf(_SC_PAGESIZE);
 	size_t aligned_sz = ((sz + page_sz - 1) / page_sz) * page_sz;
 
-	if (!posix_memalign(&p, page_sz, aligned_sz))
+	if (aligned_sz >= sz && !posix_memalign(&p, page_sz, aligned_sz))
 		return p;
 
 	return NULL;