[lld] b01bfdf - [lld][MachO] Fix UB after D103006

[Vitaly Buka via llvm-commits]

Author: Vitaly Buka
Date: 2021-06-14T21:15:54-07:00
New Revision: b01bfdfda64b684965cd7f97e99e4b0bce5d67fa

URL: https://github.com/llvm/llvm-project/commit/b01bfdfda64b684965cd7f97e99e4b0bce5d67fa
DIFF: https://github.com/llvm/llvm-project/commit/b01bfdfda64b684965cd7f97e99e4b0bce5d67fa.diff

LOG: [lld][MachO] Fix UB after D103006

ubsan detected:
lld/MachO/SyntheticSections.cpp:636:15: runtime error: null pointer
passed as argument 2, which is declared to never be null

Added: 
    

Modified: 
    lld/MachO/SyntheticSections.cpp

Removed: 
    


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diff  --git a/lld/MachO/SyntheticSections.cpp b/lld/MachO/SyntheticSections.cpp
index 458bbaa289f4..ef84a9d7c0e8 100644
--- a/lld/MachO/SyntheticSections.cpp
+++ b/lld/MachO/SyntheticSections.cpp
@@ -633,7 +633,8 @@ void DataInCodeSection::finalizeContents() {
 }
 
 void DataInCodeSection::writeTo(uint8_t *buf) const {
-  memcpy(buf, entries.data(), getRawSize());
+  if (!entries.empty())
+    memcpy(buf, entries.data(), getRawSize());
 }
 
 FunctionStartsSection::FunctionStartsSection()