messages: ensure unsigned value does not wrap

bkueng · bkueng · commit 30e885e9f61d · 2025-03-18T11:10:34.000+01:00
diff --git a/ulog_cpp/messages.hpp b/ulog_cpp/messages.hpp
@@ -430,7 +430,7 @@ class Value {
     T v;
     int total_offset = offset + array_offset * sizeof(T);
     if (backing_start > backing_end ||
-        backing_end - backing_start - total_offset < static_cast<int64_t>(sizeof(v))) {
+        backing_end - backing_start < static_cast<int64_t>(sizeof(v)) + total_offset) {
       throw AccessException("Unexpected data type size");
     }
     std::copy(backing_start + total_offset, backing_start + total_offset + sizeof(v),

Original file line number	Diff line number	Diff line change
`@@ -430,7 +430,7 @@ class Value {`
`430`	`430`	`T v;`
`431`	`431`	`int total_offset = offset + array_offset * sizeof(T);`
`432`	`432`	`if (backing_start > backing_end \|\|`
`433`		`- backing_end - backing_start - total_offset < static_cast<int64_t>(sizeof(v))) {`
	`433`	`+ backing_end - backing_start < static_cast<int64_t>(sizeof(v)) + total_offset) {`
`434`	`434`	`throw AccessException("Unexpected data type size");`
`435`	`435`	`}`
`436`	`436`	`std::copy(backing_start + total_offset, backing_start + total_offset + sizeof(v),`