[llvm] r285777 - Bitcode: Check file size before reading bitcode header.

[Peter Collingbourne via llvm-commits]

Author: pcc
Date: Tue Nov  1 19:39:11 2016
New Revision: 285777

URL: http://llvm.org/viewvc/llvm-project?rev=285777&view=rev
Log:
Bitcode: Check file size before reading bitcode header.

Should unbreak ocaml binding tests.

Also added an llvm-dis test that checks for the same thing.

Added:
    llvm/trunk/test/Bitcode/Inputs/invalid-empty.bc
Modified:
    llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp
    llvm/trunk/test/Bitcode/invalid.test

Modified: llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp?rev=285777&r1=285776&r2=285777&view=diff
==============================================================================
--- llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp (original)
+++ llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp Tue Nov  1 19:39:11 2016
@@ -4144,7 +4144,8 @@ std::error_code BitcodeReader::parseModu
 /// Helper to read the header common to all bitcode files.
 static bool hasValidBitcodeHeader(BitstreamCursor &Stream) {
   // Sniff for the signature.
-  if (Stream.Read(8) != 'B' ||
+  if (!Stream.canSkipToPos(4) ||
+      Stream.Read(8) != 'B' ||
       Stream.Read(8) != 'C' ||
       Stream.Read(4) != 0x0 ||
       Stream.Read(4) != 0xC ||

Added: llvm/trunk/test/Bitcode/Inputs/invalid-empty.bc
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Bitcode/Inputs/invalid-empty.bc?rev=285777&view=auto
==============================================================================
    (empty)

Modified: llvm/trunk/test/Bitcode/invalid.test
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Bitcode/invalid.test?rev=285777&r1=285776&r2=285777&view=diff
==============================================================================
--- llvm/trunk/test/Bitcode/invalid.test (original)
+++ llvm/trunk/test/Bitcode/invalid.test Tue Nov  1 19:39:11 2016
@@ -1,3 +1,5 @@
+RUN: not llvm-dis -disable-output %p/Inputs/invalid-empty.bc 2>&1 | \
+RUN:   FileCheck --check-prefix=INVALID-EMPTY %s
 RUN: not llvm-dis -disable-output %p/Inputs/invalid-pr20485.bc 2>&1 | \
 RUN:   FileCheck --check-prefix=INVALID-ENCODING %s
 RUN: not llvm-dis -disable-output %p/Inputs/invalid-abbrev.bc 2>&1 | \
@@ -27,6 +29,7 @@ RUN:   FileCheck --check-prefix=MISMATCH
 RUN: not llvm-dis -disable-output %p/Inputs/invalid-invoke-non-function-explicit-type.bc 2>&1 | \
 RUN:   FileCheck --check-prefix=NON-FUNCTION-EXPLICIT-INVOKE %s
 
+INVALID-EMPTY: Invalid bitcode signature
 INVALID-ENCODING: Invalid encoding
 BAD-ABBREV: Abbreviation starts with an Array or a Blob
 UNEXPECTED-EOF: Unexpected end of file