[lld] c8466a5 - Avoid a possible one-byte OOB read off of .drectve sections

[Reid Kleckner via llvm-commits]

Author: Reid Kleckner
Date: 2020-12-09T13:32:28-08:00
New Revision: c8466a57310a0f10563e4a5a511e8c6386599cfe

URL: https://github.com/llvm/llvm-project/commit/c8466a57310a0f10563e4a5a511e8c6386599cfe
DIFF: https://github.com/llvm/llvm-project/commit/c8466a57310a0f10563e4a5a511e8c6386599cfe.diff

LOG: Avoid a possible one-byte OOB read off of .drectve sections

Pointed out by Ryan Prichard

Added: 
    

Modified: 
    lld/COFF/DriverUtils.cpp

Removed: 
    


################################################################################
diff  --git a/lld/COFF/DriverUtils.cpp b/lld/COFF/DriverUtils.cpp
index f289e66dc6d5..19964428050b 100644
--- a/lld/COFF/DriverUtils.cpp
+++ b/lld/COFF/DriverUtils.cpp
@@ -883,8 +883,10 @@ ParsedDirectives ArgParser::parseDirectives(StringRef s) {
              tok.startswith_lower("-include:"))
       result.includes.push_back(tok.substr(strlen("/include:")));
     else {
-      // Save non-null-terminated strings to make proper C strings.
-      bool HasNul = tok.data()[tok.size()] == '\0';
+      // Copy substrings that are not valid C strings. The tokenizer may have
+      // already copied quoted arguments for us, so those do not need to be
+      // copied again.
+      bool HasNul = tok.end() != s.end() && tok.data()[tok.size()] == '\0';
       rest.push_back(HasNul ? tok.data() : saver.save(tok).data());
     }
   }