core/crypto: Enforce aliasing restrictions

core/crypto/chacha20/chacha20.odin

@@ -7,6 +7,7 @@ See:
 */
 package chacha20
 
+import "core:bytes"
 import "core:encoding/endian"
 import "core:math/bits"
 import "core:mem"
@@ -121,14 +122,15 @@ seek :: proc(ctx: ^Context, block_nr: u64) {
 xor_bytes :: proc(ctx: ^Context, dst, src: []byte) {
 	assert(ctx._is_initialized)
 
-	// TODO: Enforcing that dst and src alias exactly or not at all
-	// is a good idea, though odd aliasing should be extremely uncommon.
-
 	src, dst := src, dst
 	if dst_len := len(dst); dst_len < len(src) {
 		src = src[:dst_len]
 	}
 
+	if bytes.alias_inexactly(dst, src) {
+		panic("crypto/chacha20: dst and src alias inexactly")
+	}
+
 	for remaining := len(src); remaining > 0; {
 		// Process multiple blocks at once
 		if ctx._off == _BLOCK_SIZE {