Fix a crash in llvm-objdump when printing a bad x86_64 relocation in a Mach-O

file with a bad section number.

rdar://35207539

llvm-svn: 317373

3 files changed, 16 insertions, 2 deletions

diff --git a/llvm/test/tools/llvm-objdump/X86/Inputs/macho-invalid-reloc-section-index b/llvm/test/tools/llvm-objdump/X86/Inputs/macho-invalid-reloc-section-index
new file mode 100644
index 00000000000..a9d0b48449b
--- /dev/null
+++ b/llvm/test/tools/llvm-objdump/X86/Inputs/macho-invalid-reloc-section-index
diff --git a/llvm/test/tools/llvm-objdump/X86/malformed-machos.test b/llvm/test/tools/llvm-objdump/X86/malformed-machos.test
index 292666a3725..e29df464a4e 100644
--- a/llvm/test/tools/llvm-objdump/X86/malformed-machos.test
+++ b/llvm/test/tools/llvm-objdump/X86/malformed-machos.test
@@ -66,3 +66,6 @@ INVALID-SYMBOL-LIB_ORDINAL: macho-invalid-symbol-lib_ordinal': truncated or malf
 
 RUN: not llvm-objdump -macho -objc-meta-data %p/Inputs/macho-invalid-bind-entry 2>&1 | FileCheck -check-prefix INVALID-BIND-ENTRY %s
 INVALID-BIND-ENTRY: macho-invalid-bind-entry': truncated or malformed object (for BIND_OPCODE_SET_DYLIB_ORDINAL_ULEB bad library ordinal: 83 (max 0) for opcode at: 0x0)
+
+RUN: llvm-objdump -macho -r %p/Inputs/macho-invalid-reloc-section-index | FileCheck -check-prefix INVALID-RELOC-SECTION-INDEX %s
+INVALID-RELOC-SECTION-INDEX: 0000000000000021 X86_64_RELOC_UNSIGNED 8388613 (?,?)
diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index d80f1cb049d..02eaa89f088 100644
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -865,8 +865,19 @@ static void printRelocationTargetName(const MachOObjectFile *O,
   } else {
     section_iterator SI = O->section_begin();
     // Adjust for the fact that sections are 1-indexed.
-    advance(SI, Val - 1);
-    SI->getName(S);
+    if (Val == 0) {
+      fmt << "0 (?,?)";
+      return;
+    }
+    uint32_t i = Val - 1;
+    while (i != 0 && SI != O->section_end()) {
+      i--;
+      advance(SI, 1);
+    }
+    if (SI == O->section_end())
+      fmt << Val << " (?,?)";
+    else
+      SI->getName(S);
   }
 
   fmt << S;