Have gold's File_read::do_read() function check the start parameter

PR 23765
	* fileread.cc (File_read::do_read): Check start parameter before
	computing number of bytes to read.

gold/ChangeLog

@@ -1,3 +1,9 @@
+2022-06-27  Nick Clifton  <nickc@redhat.com>
+
+	PR 23765
+	* fileread.cc (File_read::do_read): Check start parameter before
+	computing number of bytes to read.
+
 2022-05-18  Nick Clifton  <nickc@redhat.com>
 
 	* int_encoding.cc (get_length_as_unsigned_LEB_128): Remove

gold/fileread.cc

@@ -385,6 +385,12 @@ File_read::do_read(off_t start, section_size_type size, void* p)
   ssize_t bytes;
   if (this->whole_file_view_ != NULL)
     {
+      // See PR 23765 for an example of a testcase that triggers this error.
+      if (((ssize_t) start) < 0)
+	gold_fatal(_("%s: read failed, starting offset (%#llx) less than zero"),
+		   this->filename().c_str(),
+		   static_cast<long long>(start));
+	
       bytes = this->size_ - start;
       if (static_cast<section_size_type>(bytes) >= size)
 	{