llvm-objdump: handle stubbed and malformed dylibs better

We were quite happy to read past the end of the valid section data when
disassembling. Instead we entirely skip stub dylibs, and tell the user what's
happened if their section only has partial data.

llvm-svn: 275487

5 files changed, 24 insertions, 2 deletions

diff --git a/llvm/test/tools/llvm-objdump/X86/Inputs/stubbed.dylib.macho-x86_64 b/llvm/test/tools/llvm-objdump/X86/Inputs/stubbed.dylib.macho-x86_64
new file mode 100755
index 00000000000..144738bc97d
--- /dev/null
+++ b/llvm/test/tools/llvm-objdump/X86/Inputs/stubbed.dylib.macho-x86_64
diff --git a/llvm/test/tools/llvm-objdump/X86/Inputs/truncated-section.dylib.macho-x86_64 b/llvm/test/tools/llvm-objdump/X86/Inputs/truncated-section.dylib.macho-x86_64
new file mode 100755
index 00000000000..a099ee2d379
--- /dev/null
+++ b/llvm/test/tools/llvm-objdump/X86/Inputs/truncated-section.dylib.macho-x86_64
diff --git a/llvm/test/tools/llvm-objdump/X86/stubbed-dylib.test b/llvm/test/tools/llvm-objdump/X86/stubbed-dylib.test
new file mode 100644
index 00000000000..6f7f7221eb1
--- /dev/null
+++ b/llvm/test/tools/llvm-objdump/X86/stubbed-dylib.test
@@ -0,0 +1,5 @@
+RUN: llvm-objdump -macho -d %p/Inputs/stubbed.dylib.macho-x86_64 | FileCheck %s
+
+CHECK: (__TEXT,__text) section
+CHECK-NOT: func
+CHECK-NOT: func2
diff --git a/llvm/test/tools/llvm-objdump/X86/truncated-section.test b/llvm/test/tools/llvm-objdump/X86/truncated-section.test
new file mode 100644
index 00000000000..e9fe75da71a
--- /dev/null
+++ b/llvm/test/tools/llvm-objdump/X86/truncated-section.test
@@ -0,0 +1,7 @@
+RUN: llvm-objdump -macho -d %p/Inputs/truncated-section.dylib.macho-x86_64 | FileCheck %s
+
+CHECK: _func:
+CHECK:     retq
+CHECK:     retq
+
+CHECK: section data ends, _func2 lies outside valid range
diff --git a/llvm/tools/llvm-objdump/MachODump.cpp b/llvm/tools/llvm-objdump/MachODump.cpp
index 08bc1f48240..991ccee47a5 100644
--- a/llvm/tools/llvm-objdump/MachODump.cpp
+++ b/llvm/tools/llvm-objdump/MachODump.cpp
@@ -6662,6 +6662,10 @@ static void DisassembleMachO(StringRef Filename, MachOObjectFile *MachOOF,
 
     unsigned int Arch = MachOOF->getArch();
 
+    // Skip all symbols if this is a stubs file.
+    if (Bytes.size() == 0)
+      return;
+
     // Disassemble symbol by symbol.
     for (unsigned SymIdx = 0; SymIdx != Symbols.size(); SymIdx++) {
       Expected<StringRef> SymNameOrErr = Symbols[SymIdx].getName();
@@ -6716,10 +6720,17 @@ static void DisassembleMachO(StringRef Filename, MachOObjectFile *MachOOF,
         continue;
 
       // Start at the address of the symbol relative to the section's address.
+      uint64_t SectSize = Sections[SectIdx].getSize();
       uint64_t Start = Symbols[SymIdx].getValue();
       uint64_t SectionAddress = Sections[SectIdx].getAddress();
       Start -= SectionAddress;
 
+      if (Start > SectSize) {
+        outs() << "section data ends, " << SymName
+               << " lies outside valid range\n";
+        return;
+      }
+
       // Stop disassembling either at the beginning of the next symbol or at
       // the end of the section.
       bool containsNextSym = false;
@@ -6745,8 +6756,7 @@ static void DisassembleMachO(StringRef Filename, MachOObjectFile *MachOOF,
         ++NextSymIdx;
       }
 
-      uint64_t SectSize = Sections[SectIdx].getSize();
-      uint64_t End = containsNextSym ? NextSym : SectSize;
+      uint64_t End = containsNextSym ? std::min(NextSym, SectSize) : SectSize;
       uint64_t Size;
 
       symbolTableWorked = true;