From c3ccd67d726a284addde38c9d96dda666143274a Mon Sep 17 00:00:00 2001
From: Filipe Cabecinhas <me@filcab.net>
Date: Tue, 19 May 2015 00:34:17 +0000
Subject: [PATCH] [BitcodeReader] It's a malformed block if CodeLenWidth is too
 big

Bug found with AFL fuzz.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@237646 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Bitcode/Reader/BitstreamReader.cpp        |   4 ++++
 test/Bitcode/Inputs/invalid-code-len-width.bc | Bin 0 -> 173 bytes
 test/Bitcode/invalid.test                     |   5 +++++
 3 files changed, 9 insertions(+)
 create mode 100644 test/Bitcode/Inputs/invalid-code-len-width.bc

diff --git a/lib/Bitcode/Reader/BitstreamReader.cpp b/lib/Bitcode/Reader/BitstreamReader.cpp
index dff6d181486..450bbbc4558 100644
--- a/lib/Bitcode/Reader/BitstreamReader.cpp
+++ b/lib/Bitcode/Reader/BitstreamReader.cpp
@@ -39,6 +39,10 @@ bool BitstreamCursor::EnterSubBlock(unsigned BlockID, unsigned *NumWordsP) {
 
   // Get the codesize of this block.
   CurCodeSize = ReadVBR(bitc::CodeLenWidth);
+  // We can't read more than MaxChunkSize at a time
+  if (CurCodeSize > MaxChunkSize)
+    return true;
+
   SkipToFourByteBoundary();
   unsigned NumWords = Read(bitc::BlockSizeWidth);
   if (NumWordsP) *NumWordsP = NumWords;
diff --git a/test/Bitcode/Inputs/invalid-code-len-width.bc b/test/Bitcode/Inputs/invalid-code-len-width.bc
new file mode 100644
index 0000000000000000000000000000000000000000..c8e8c4f66538931187d3cfbe3b80c1f1ee3ce76f
GIT binary patch
literal 173
zcmZ>AK5$Qw=NUsD0|NthlLEv4|Nk3={=Z;gZ&aS>B=G-#y?~MBB*qpVRaOp3IhO9E
z1_4(lr%BvSEdoX&790{~0t_xH9$XU?m2EqmEn1qT&oJAbaJKDXwgsA3sKCI$2BgI{
zDD=9x1hXCqYG7e7EK*@V!y%ZoV!;ZBV;=-q7#KRa85sD1%8ZmaI2BS_S%j6Aw6HV?
QDqc-<aA`?l2Fkzy094;B@Bjb+

literal 0
HcmV?d00001

diff --git a/test/Bitcode/invalid.test b/test/Bitcode/invalid.test
index 921d4e62c04..c4c635e08d3 100644
--- a/test/Bitcode/invalid.test
+++ b/test/Bitcode/invalid.test
@@ -147,3 +147,8 @@ RUN: not llvm-dis -disable-output %p/Inputs/invalid-inserted-value-type-mismatch
 RUN:   FileCheck --check-prefix=INSERT-TYPE-MISMATCH %s
 
 INSERT-TYPE-MISMATCH: Inserted value type doesn't match aggregate type
+
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-code-len-width.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=INVALID-CODELENWIDTH %s
+
+INVALID-CODELENWIDTH: Malformed block
-- 
2.34.1