ELF: Don't process the partition end marker during combineEhSections().

Otherwise the getPartition() accessor may return an OOB pointer. Found
using _GLIBCXX_DEBUG.

The error is benign (we never dereference the pointer for the end marker)
so this wasn't caught by e.g. the sanitizer bots.

llvm-svn: 363026

1 files changed, 4 insertions, 2 deletions

diff --git a/lld/ELF/Writer.cpp b/lld/ELF/Writer.cpp
index 6614d9c4076..c6ba893db0b 100644
--- a/lld/ELF/Writer.cpp
+++ b/lld/ELF/Writer.cpp
@@ -178,7 +178,9 @@ template <class ELFT> static void copySectionsIntoPartitions() {
 
 template <class ELFT> static void combineEhSections() {
   for (InputSectionBase *&S : InputSections) {
-    if (!S->isLive())
+    // Ignore dead sections and the partition end marker (.part.end),
+    // whose partition number is out of bounds.
+    if (!S->isLive() || S->Partition == 255)
       continue;
 
     Partition &Part = S->getPartition();
@@ -442,7 +444,7 @@ template <class ELFT> static void createSyntheticSections() {
   if (Partitions.size() != 1) {
     // Create the partition end marker. This needs to be in partition number 255
     // so that it is sorted after all other partitions. It also has other
-    // special handling (see createPhdrs()).
+    // special handling (see createPhdrs() and combineEhSections()).
     In.PartEnd = make<BssSection>(".part.end", Config->MaxPageSize, 1);
     In.PartEnd->Partition = 255;
     Add(In.PartEnd);