[llvm-objdump] Don't attempt to print lines beyond the end of file

This may trigger a segfault in llvm-objdump when the line number stored
in debug infromation points beyond the end of file; lines in LineBuffer
are stored in std::vector which is allocated in chunks, so even if the
debug info points beyond the end of the file, this doesn't necessarily
trigger the segfault unless the line number points beyond the allocated
space.

Differential Revision: https://reviews.llvm.org/D32466

llvm-svn: 301347

diff --git a/llvm/test/tools/llvm-objdump/X86/Inputs/debug-info-fileinfo.exe.elf-x86_64 b/llvm/test/tools/llvm-objdump/X86/Inputs/debug-info-fileinfo.exe.elf-x86_64
new file mode 100644 (file)
index 0000000..2074886
Binary files /dev/null and b/llvm/test/tools/llvm-objdump/X86/Inputs/debug-info-fileinfo.exe.elf-x86_64 differ

diff --git a/llvm/test/tools/llvm-objdump/X86/debug-info-fileinfo.test b/llvm/test/tools/llvm-objdump/X86/debug-info-fileinfo.test
new file mode 100644 (file)
index 0000000..2c51e0b
--- /dev/null
+++ b/llvm/test/tools/llvm-objdump/X86/debug-info-fileinfo.test
@@ -0,0 +1,27 @@
+# Check that debug info line number pointing beyond the end of the file
+# doesn't cause a segmentation fault in llvm-objdump.
+
+# To rebuild the input: clang -g debug-info-fileinfo.S -o debug-info-fileinfo.exe -nostdlib
+
+# RUN: llvm-objdump -S %p/Inputs/debug-info-fileinfo.exe.elf-x86_64 | FileCheck %s
+
+# CHECK: Disassembly of section .text:
+# CHECK: _start
+# CHECK-NEXT:   400078:       c3      retq
+# CHECK: foo
+# CHECK-NEXT:   400079:       90      nop
+# CHECK-NEXT:   40007a:       90      nop
+# CHECK-NEXT:   40007b:       c3      retq
+
+.text
+
+.global _start; .type _start, STT_FUNC; _start:
+    ret
+
+.global foo; .type foo, STT_FUNC; foo:
+    # foo
+    # bar
+    # baz
+    nop
+    nop
+    ret

diff --git a/llvm/tools/llvm-objdump/llvm-objdump.cpp b/llvm/tools/llvm-objdump/llvm-objdump.cpp
index 613d064..18fa0e0 100644 (file)
--- a/llvm/tools/llvm-objdump/llvm-objdump.cpp
+++ b/llvm/tools/llvm-objdump/llvm-objdump.cpp
@@ -485,10 +485,13 @@ void SourcePrinter::printSourceLine(raw_ostream &OS, uint64_t Address,
     auto FileBuffer = SourceCache.find(LineInfo.FileName);
     if (FileBuffer != SourceCache.end()) {
       auto LineBuffer = LineCache.find(LineInfo.FileName);
-      if (LineBuffer != LineCache.end())
+      if (LineBuffer != LineCache.end()) {
+        if (LineInfo.Line > LineBuffer->second.size())
+          return;
         // Vector begins at 0, line numbers are non-zero
         OS << Delimiter << LineBuffer->second[LineInfo.Line - 1].ltrim()
            << "\n";
+      }
     }
   }
   OldLineInfo = LineInfo;