[llvm] r316143 - Fix buffer overflow.

[Rafael Espindola via llvm-commits]

Author: rafael
Date: Wed Oct 18 18:25:48 2017
New Revision: 316143

URL: http://llvm.org/viewvc/llvm-project?rev=316143&view=rev
Log:
Fix buffer overflow.

We were reading past the end of the buffer.

Added:
    llvm/trunk/test/Object/Inputs/invalid-coff-header-too-small
Modified:
    llvm/trunk/lib/BinaryFormat/Magic.cpp
    llvm/trunk/test/Object/invalid.test

Modified: llvm/trunk/lib/BinaryFormat/Magic.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/BinaryFormat/Magic.cpp?rev=316143&r1=316142&r2=316143&view=diff
==============================================================================
--- llvm/trunk/lib/BinaryFormat/Magic.cpp (original)
+++ llvm/trunk/lib/BinaryFormat/Magic.cpp Wed Oct 18 18:25:48 2017
@@ -185,7 +185,7 @@ file_magic llvm::identify_magic(StringRe
     if (startswith(Magic, "MZ") && Magic.size() >= 0x3c + 4) {
       uint32_t off = read32le(Magic.data() + 0x3c);
       // PE/COFF file, either EXE or DLL.
-      if (off < Magic.size() &&
+      if (off + sizeof(COFF::PEMagic) <= Magic.size() &&
           memcmp(Magic.data() + off, COFF::PEMagic, sizeof(COFF::PEMagic)) == 0)
         return file_magic::pecoff_executable;
     }

Added: llvm/trunk/test/Object/Inputs/invalid-coff-header-too-small
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Object/Inputs/invalid-coff-header-too-small?rev=316143&view=auto
==============================================================================
Binary files llvm/trunk/test/Object/Inputs/invalid-coff-header-too-small (added) and llvm/trunk/test/Object/Inputs/invalid-coff-header-too-small Wed Oct 18 18:25:48 2017 differ

Modified: llvm/trunk/test/Object/invalid.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Object/invalid.test?rev=316143&r1=316142&r2=316143&view=diff
==============================================================================
--- llvm/trunk/test/Object/invalid.test (original)
+++ llvm/trunk/test/Object/invalid.test Wed Oct 18 18:25:48 2017
@@ -86,3 +86,6 @@ INVALID-REL-SYM: invalid section offset
 
 RUN: not llvm-readobj -r %p/Inputs/invalid-buffer.elf 2>&1 | FileCheck --check-prefix=INVALID-BUFFER %s
 INVALID-BUFFER: Invalid buffer
+
+RUN: not llvm-readobj %p/Inputs/invalid-coff-header-too-small 2>&1 | FileCheck --check-prefix=COFF-HEADER %s
+COFF-HEADER: The file was not recognized as a valid object file