From 1a7f03ef84da74bfde2dfe8d9d8ef530ad390da4 Mon Sep 17 00:00:00 2001
From: Benjamin Kramer <benny.kra@googlemail.com>
Date: Thu, 31 Aug 2017 12:27:10 +0000
Subject: [PATCH] [Object] Verify object sizes before handing out StringRefs
 pointing out of bounds.

This can only happen on corrupt input. Found by OSS-FUZZ!
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=3228

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@312235 91177308-0d34-0410-b5e6-96231b3b80d8
---
 include/llvm/Object/Binary.h                     |  11 +++++++++++
 include/llvm/Object/ELFObjectFile.h              |   4 ++++
 lib/Object/COFFObjectFile.cpp                    |  15 +++------------
 .../dwarfdump-decompression-corrupt.elf-x86-64   | Bin 0 -> 120 bytes
 .../dwarfdump-decompression-corrupt.test         |   6 ++++++
 5 files changed, 24 insertions(+), 12 deletions(-)
 create mode 100644 test/DebugInfo/Inputs/dwarfdump-decompression-corrupt.elf-x86-64
 create mode 100644 test/DebugInfo/dwarfdump-decompression-corrupt.test

diff --git a/include/llvm/Object/Binary.h b/include/llvm/Object/Binary.h
index 3f5a233c1ee..d09879777e2 100644
--- a/include/llvm/Object/Binary.h
+++ b/include/llvm/Object/Binary.h
@@ -15,6 +15,7 @@
 #define LLVM_OBJECT_BINARY_H
 
 #include "llvm/ADT/Triple.h"
+#include "llvm/Object/Error.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include <algorithm>
@@ -143,6 +144,16 @@ public:
       return Triple::ELF;
     return Triple::UnknownObjectFormat;
   }
+
+  static std::error_code checkOffset(MemoryBufferRef M, uintptr_t Addr,
+                                     const uint64_t Size) {
+    if (Addr + Size < Addr || Addr + Size < Size ||
+        Addr + Size > uintptr_t(M.getBufferEnd()) ||
+        Addr < uintptr_t(M.getBufferStart())) {
+      return object_error::unexpected_eof;
+    }
+    return std::error_code();
+  }
 };
 
 /// @brief Create a Binary from Source, autodetecting the file type.
diff --git a/include/llvm/Object/ELFObjectFile.h b/include/llvm/Object/ELFObjectFile.h
index 73011f6f9fe..f436e4534ce 100644
--- a/include/llvm/Object/ELFObjectFile.h
+++ b/include/llvm/Object/ELFObjectFile.h
@@ -667,6 +667,10 @@ std::error_code
 ELFObjectFile<ELFT>::getSectionContents(DataRefImpl Sec,
                                         StringRef &Result) const {
   const Elf_Shdr *EShdr = getSection(Sec);
+  if (std::error_code EC =
+          checkOffset(getMemoryBufferRef(),
+                      (uintptr_t)base() + EShdr->sh_offset, EShdr->sh_size))
+    return EC;
   Result = StringRef((const char *)base() + EShdr->sh_offset, EShdr->sh_size);
   return std::error_code();
 }
diff --git a/lib/Object/COFFObjectFile.cpp b/lib/Object/COFFObjectFile.cpp
index 0a2053477ca..f88ebfc9a1d 100644
--- a/lib/Object/COFFObjectFile.cpp
+++ b/lib/Object/COFFObjectFile.cpp
@@ -52,16 +52,6 @@ static bool checkSize(MemoryBufferRef M, std::error_code &EC, uint64_t Size) {
   return true;
 }
 
-static std::error_code checkOffset(MemoryBufferRef M, uintptr_t Addr,
-                                   const uint64_t Size) {
-  if (Addr + Size < Addr || Addr + Size < Size ||
-      Addr + Size > uintptr_t(M.getBufferEnd()) ||
-      Addr < uintptr_t(M.getBufferStart())) {
-    return object_error::unexpected_eof;
-  }
-  return std::error_code();
-}
-
 // Sets Obj unless any bytes in [addr, addr + size) fall outsize of m.
 // Returns unexpected_eof if error.
 template <typename T>
@@ -69,7 +59,7 @@ static std::error_code getObject(const T *&Obj, MemoryBufferRef M,
                                  const void *Ptr,
                                  const uint64_t Size = sizeof(T)) {
   uintptr_t Addr = uintptr_t(Ptr);
-  if (std::error_code EC = checkOffset(M, Addr, Size))
+  if (std::error_code EC = Binary::checkOffset(M, Addr, Size))
     return EC;
   Obj = reinterpret_cast<const T *>(Addr);
   return std::error_code();
@@ -383,7 +373,8 @@ getFirstReloc(const coff_section *Sec, MemoryBufferRef M, const uint8_t *Base) {
     // relocations.
     begin++;
   }
-  if (checkOffset(M, uintptr_t(begin), sizeof(coff_relocation) * NumRelocs))
+  if (Binary::checkOffset(M, uintptr_t(begin),
+                          sizeof(coff_relocation) * NumRelocs))
     return nullptr;
   return begin;
 }
diff --git a/test/DebugInfo/Inputs/dwarfdump-decompression-corrupt.elf-x86-64 b/test/DebugInfo/Inputs/dwarfdump-decompression-corrupt.elf-x86-64
new file mode 100644
index 0000000000000000000000000000000000000000..d3b0b38a92f2c180d843aaa410e805d323be576d
GIT binary patch
literal 120
ucmb<-^>JflR6v0L{}uitcnTT}3=9aa1_Kj_{~xFb2LMV#)Z<hE(Fg!al@vq(

literal 0
HcmV?d00001

diff --git a/test/DebugInfo/dwarfdump-decompression-corrupt.test b/test/DebugInfo/dwarfdump-decompression-corrupt.test
new file mode 100644
index 00000000000..93f5360c0af
--- /dev/null
+++ b/test/DebugInfo/dwarfdump-decompression-corrupt.test
@@ -0,0 +1,6 @@
+REQUIRES: zlib
+
+// dwarfdump-decompression-corrupt.elf-x86-64 is fuzzer output
+RUN: llvm-dwarfdump %p/Inputs/dwarfdump-decompression-corrupt.elf-x86-64 2>&1 | FileCheck %s
+
+CHECK: error: failed to decompress '', corrupted compressed section header
-- 
2.50.1