all: final cleanups in preparation for release

src/util/membuffer.cpp

@@ -62,6 +62,7 @@ static noinline void init_use_simple_mcheck() noexcept {
 static bool use_simple_mcheck() noexcept {
     static upx_std_once_flag init_done;
     upx_std_call_once(init_done, init_use_simple_mcheck);
+    // NOTE: clang-analyzer-unix.Malloc does not know that this flag is "constant"
     return use_simple_mcheck_flag;
 }
 #else
@@ -195,7 +196,7 @@ void MemBuffer::checkState() const {
 }
 
 void MemBuffer::alloc(upx_uint64_t bytes) {
-    // NOTE: we don't automatically free a used buffer
+    // INFO: we don't automatically free a used buffer
     assert(ptr == nullptr);
     assert(size_in_bytes == 0);
     //
@@ -254,9 +255,9 @@ void MemBuffer::dealloc() noexcept {
             set_ne32(p + size_in_bytes, 0);
             set_ne32(p + size_in_bytes + 4, 0);
             //
-            ::free(p - 16);
+            ::free(p - 16); // NOLINT(clang-analyzer-unix.Malloc) // see NOTE above
         } else {
-            ::free(ptr);
+            ::free(ptr); // NOLINT(clang-analyzer-unix.Malloc) // see NOTE above
         }
         ptr = nullptr;
         size_in_bytes = 0;

src/util/xspan.cpp

@@ -76,7 +76,11 @@ void xspan_check_range(const void *ptr, const void *base, ptrdiff_t size_in_byte
         xspan_fail_range_nullptr();
     if very_unlikely (base == nullptr)
         xspan_fail_range_nullbase();
-    ptrdiff_t off = (const charptr) ptr - (const charptr) base;
+#if defined(__SANITIZE_ADDRESS__)
+    const acc_intptr_t off = (acc_uintptr_t) ptr - (acc_uintptr_t) base;
+#else
+    const ptrdiff_t off = (const charptr) ptr - (const charptr) base;
+#endif
     if very_unlikely (off < 0 || off > size_in_bytes || size_in_bytes > UPX_RSIZE_MAX)
         xspan_fail_range_range();
     NO_fprintf(stderr, "xspan_check_range done\n");

src/util/xspan_impl.h

@@ -206,6 +206,16 @@ struct XSpanInternalDummyArg {
 
 XSPAN_NAMESPACE_END
 
+// poison a pointer: point to a non-null invalid address
+// - resulting pointer should crash on dereference
+// - this should be efficient (so no mmap() guard page etc.)
+// - this should play nice with runtime checkers like ASAN, valgrind, etc.
+// - this should play nice with static analyzers like clang-tidy
+static forceinline void *XSPAN_GET_POISON_VOID_PTR() {
+    // return (void *) (upx_uintptr_t) 16; // NOLINT(performance-no-int-to-ptr)
+    return (void *) 16;
+}
+
 #ifndef XSPAN_DELETED_FUNCTION
 #define XSPAN_DELETED_FUNCTION = delete
 #endif

src/util/xspan_impl_common.h

@@ -114,7 +114,7 @@ forceinline ~CSelf() noexcept {}
     noinline void invalidate() {
         assertInvariants();
         // poison the pointer: point to non-null invalid address
-        ptr = (pointer) (void *) (upx_uintptr_t) 16; // NOLINT(performance-no-int-to-ptr)
+        ptr = (pointer) XSPAN_GET_POISON_VOID_PTR();
         // ptr = (pointer) (void *) &ptr; // point to self
         base = ptr;
         size_in_bytes = 0;

src/util/xspan_impl_ptr.h

@@ -78,7 +78,7 @@ public:
     noinline void invalidate() {
         assertInvariants();
         // poison the pointer: point to non-null invalid address
-        ptr = (pointer) (void *) (upx_uintptr_t) 16; // NOLINT(performance-no-int-to-ptr)
+        ptr = (pointer) XSPAN_GET_POISON_VOID_PTR();
         // ptr = (pointer) (void *) &ptr; // point to self
         assertInvariants();
     }