A Heap-buffer-overflow problem was discovered in WasmBinaryBuilder::getFunctionIndexName(unsigned int)

[wcventure]

Hi, there.

A Heap-buffer-overflow problem was discovered in WasmBinaryBuilder::getFunctionIndexName(unsigned int). A crafted wasm input can cause segment faults and I have confirmed them with address sanitizer too.

Here are the POC files. Please use "./wasm-opt $POC" to reproduce the error.
POC.zip

git log:

commit 0e5e55053c171b138a0cf5aa8a08de8c7714048f
Author: Alon Zakai <alonzakai@gmail.com>
Date:   Sat Jan 19 05:30:43 2019 -0800

    Show a proper error on an invalid type in binary reading ; fixes #1872 (#1874)

The ASAN dumps the stack trace as follows:

=================================================================
==26011==ERROR: AddressSanitizer: heap-buffer-overflow on address 0x6060000032a0 at pc 0x0000009ae654 bp 0x7ffd831fce90 sp 0x7ffd831fce88
READ of size 8 at 0x6060000032a0 thread T0
    #0 0x9ae653 in wasm::WasmBinaryBuilder::getFunctionIndexName(unsigned int) /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/bits/unique_ptr.h:147:42
    #1 0x9ae653 in wasm::WasmBinaryBuilder::processFunctions() /home/wencheng/Documents/FuzzingObject/binaryen/src/wasm/wasm-binary.cpp:1508
    #2 0x980f41 in wasm::WasmBinaryBuilder::read() /home/wencheng/Documents/FuzzingObject/binaryen/src/wasm/wasm-binary.cpp:706:3
    #3 0xa81ed9 in wasm::ModuleReader::readBinary(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, wasm::Module&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) /home/wencheng/Documents/FuzzingObject/binaryen/src/wasm/wasm-io.cpp:52:10
    #4 0xa84b1c in wasm::ModuleReader::read(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >, wasm::Module&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >) /home/wencheng/Documents/FuzzingObject/binaryen/src/wasm/wasm-io.cpp:71:5
    #5 0x627919 in main /home/wencheng/Documents/FuzzingObject/binaryen/src/tools/wasm-opt.cpp:144:14
    #6 0x7ff28f63182f in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x2082f)
    #7 0x51c5b8 in _start (/home/wencheng/Documents/FuzzingObject/binaryen/build/bin/wasm-opt+0x51c5b8)

Address 0x6060000032a0 is a wild pointer.
SUMMARY: AddressSanitizer: heap-buffer-overflow /usr/lib/gcc/x86_64-linux-gnu/7.3.0/../../../../include/c++/7.3.0/bits/unique_ptr.h:147:42 in wasm::WasmBinaryBuilder::getFunctionIndexName(unsigned int)
Shadow bytes around the buggy address:
  0x0c0c7fff8600: fa fa fa fa 00 00 00 00 00 00 00 fa fa fa fa fa
  0x0c0c7fff8610: 00 00 00 00 00 00 00 00 fa fa fa fa fa fa fa fa
  0x0c0c7fff8620: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0c7fff8630: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0c7fff8640: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x0c0c7fff8650: fa fa fa fa[fa]fa fa fa fa fa fa fa fa fa fa fa
  0x0c0c7fff8660: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0c7fff8670: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0c7fff8680: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0c7fff8690: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x0c0c7fff86a0: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
Shadow byte legend (one shadow byte represents 8 application bytes):
  Addressable:           00
  Partially addressable: 01 02 03 04 05 06 07 
  Heap left redzone:       fa
  Freed heap region:       fd
  Stack left redzone:      f1
  Stack mid redzone:       f2
  Stack right redzone:     f3
  Stack after return:      f5
  Stack use after scope:   f8
  Global redzone:          f9
  Global init order:       f6
  Poisoned by user:        f7
  Container overflow:      fc
  Array cookie:            ac
  Intra object redzone:    bb
  ASan internal:           fe
  Left alloca redzone:     ca
  Right alloca redzone:    cb
==26011==ABORTING

[kripken]

Thanks!

This looks the same as #1879 (similar stack trace, my wip fix resolves it).