[llvm] r240357 - Fix PR23914.

[Evgeniy Stepanov]

Author: eugenis
Date: Mon Jun 22 18:36:03 2015
New Revision: 240357

URL: http://llvm.org/viewvc/llvm-project?rev=240357&view=rev
Log:
Fix PR23914.

r226830 moved the declaration of Buf to a nested scope, resulting
in a dangling reference (in StringRef Name), and a use-after-free.


Added:
    llvm/trunk/test/MC/ELF/symver-pr23914.s
Modified:
    llvm/trunk/lib/MC/ELFObjectWriter.cpp

Modified: llvm/trunk/lib/MC/ELFObjectWriter.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/MC/ELFObjectWriter.cpp?rev=240357&r1=240356&r2=240357&view=diff
==============================================================================
--- llvm/trunk/lib/MC/ELFObjectWriter.cpp (original)
+++ llvm/trunk/lib/MC/ELFObjectWriter.cpp Mon Jun 22 18:36:03 2015
@@ -842,12 +842,12 @@ void ELFObjectWriter::computeSymbolTable
     // seems that this information is not easily accessible from the
     // ELFObjectWriter.
     StringRef Name = Symbol.getName();
+    SmallString<32> Buf;
     if (!Name.startswith("?") && !Name.startswith("@?") &&
         !Name.startswith("__imp_?") && !Name.startswith("__imp_@?")) {
       // This symbol isn't following the MSVC C++ name mangling convention. We
       // can thus safely interpret the @@@ in symbol names as specifying symbol
       // versioning.
-      SmallString<32> Buf;
       size_t Pos = Name.find("@@@");
       if (Pos != StringRef::npos) {
         Buf += Name.substr(0, Pos);

Added: llvm/trunk/test/MC/ELF/symver-pr23914.s
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ELF/symver-pr23914.s?rev=240357&view=auto
==============================================================================
--- llvm/trunk/test/MC/ELF/symver-pr23914.s (added)
+++ llvm/trunk/test/MC/ELF/symver-pr23914.s Mon Jun 22 18:36:03 2015
@@ -0,0 +1,16 @@
+// Regression test for PR23914.
+// RUN: llvm-mc -filetype=obj -triple x86_64-pc-linux-gnu %s -o - | llvm-readobj -r -t | FileCheck %s
+
+defined:
+        .symver defined, aaaaaaaaaaaaaaaaaa@@@AAAAAAAAAAAAA
+
+// CHECK:      Symbol {
+// CHECK:        Name: aaaaaaaaaaaaaaaaaa@@AAAAAAAAAAAAA
+// CHECK-NEXT:   Value: 0x0
+// CHECK-NEXT:   Size: 0
+// CHECK-NEXT:   Binding: Local
+// CHECK-NEXT:   Type: None
+// CHECK-NEXT:   Other: 0
+// CHECK-NEXT:   Section: .text
+// CHECK-NEXT: }
+