Merge #370: fix: prevent silent overflow in calloc

11153bb fix: prevent silent overflow in calloc (stringhandler)

Pull request description:

  Minor overflow prevention.
  
  Overflow can silently occur in release builds. Low priority but simple enough fix.


ACKs for top commit:
  delta1:
    ACK 11153bb; tested locally
  apoelstra:
    ACK 11153bb; successfully ran local tests


Tree-SHA512: 907ff678cace034cd36f2cc0dfef1bf07c0cca673d1e2f33ac8bbf2d2bc1c4c9c86b6d5c7a9137cd587105b9e53bbcd21cef6dca8fdfd20faec79294920e61f1

Author: apoelstra

simplicity-sys/src/alloc.rs

@@ -87,7 +87,7 @@ pub unsafe extern "C" fn rust_0_7_malloc(size_bytes: usize) -> *mut u8 {
 /// Allocated bytes must be freed using [`rust_0_7_free`].
 #[no_mangle]
 pub unsafe extern "C" fn rust_0_7_calloc(num: usize, size: usize) -> *mut u8 {
-    let size_bytes = num * size;
+    let size_bytes = num.saturating_mul(size);
     // SAFETY: Allocator is `alloc_alloc_zeroed`.
     allocate(size_bytes, alloc::alloc_zeroed)
 }