[XERCESC-2094] Memory leak related to invalid encoding

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 3.1.0, 3.1.1, 3.1.2, 3.1.3, 3.1.4
• Fix Version/s: 3.2.0
• Environment: Probably all. In that case Ubuntu 16.04 x86_64
• Assignee: Scott Cantor
• Reporter: Even Rouault
• Created: 19/May/17 10:55
• Updated: 28/Aug/17 23:41
• Resolved: 13/Jul/17 22:55

Description

Issue originally found through OSS-Fuzz on GDAL ( for reference https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=1685 : the link will not be publicly accessible until 90 days have passe), but can be reproduced with Xerces-C SAX2Count utility.

On the attached file, Valgrind reports a memory leak:

The content of the file is:
{{{
<?xml[newline character]
version="1.0" encoding="U"?><foo xmlns="http://schemas.opengis.net/gml"/>
}}}

valgrind --leak-check=full /home/even/install-xerces-c-3.1.4/bin/SAX2Count xerces-c-leak.xml
==21268== Memcheck, a memory error detector
==21268== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==21268== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==21268== Command: /home/even/install-xerces-c-3.1.4/bin/SAX2Count /home/even/gdal/trunk/gdal/xerces-c-leak.xml
==21268==

Fatal Error at file /home/even/gdal/trunk/gdal/xerces-c-leak.xml, line 1, char 35
Message: unable to create converter for 'U' encoding
==21268==
==21268== HEAP SUMMARY:
==21268== in use at exit: 76,348 bytes in 10 blocks
==21268== total heap usage: 9,244 allocs, 9,234 frees, 1,282,907 bytes allocated
==21268==
==21268== 52 (40 direct, 12 indirect) bytes in 1 blocks are definitely lost in loss record 4 of 10
==21268== at 0x4C2E0EF: operator new(unsigned long) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==21268== by 0x4FF9B58: xercesc_3_1::MemoryManagerImpl::allocate(unsigned long) (MemoryManagerImpl.cpp:40)
==21268== by 0x4F7EE05: xercesc_3_1::XMemory::operator new(unsigned long, xercesc_3_1::MemoryManager*) (XMemory.cpp:68)
==21268== by 0x4F7E660: xercesc_3_1::ENameMapFor<xercesc_3_1::XMLUTF8Transcoder>::makeNew(unsigned long, xercesc_3_1::MemoryManager*) const (TransENameMap.c:50)
==21268== by 0x4F7AF20: xercesc_3_1::XMLTransService::makeNewTranscoderFor(unsigned short const*, xercesc_3_1::XMLTransService::Codes&, unsigned long, xercesc_3_1::MemoryManager*) (TransService.cpp:147)
==21268== by 0x5010A75: xercesc_3_1::XMLReader::refreshCharBuffer() (XMLReader.cpp:523)
==21268== by 0x4FFA5AA: peekNextChar (XMLReader.hpp:767)
==21268== by 0x4FFA5AA: xercesc_3_1::ReaderMgr::peekNextChar() (ReaderMgr.cpp:158)
==21268== by 0x5016297: xercesc_3_1::XMLScanner::scanProlog() (XMLScanner.cpp:1238)
==21268== by 0x4FEE371: xercesc_3_1::IGXMLScanner::scanDocument(xercesc_3_1::InputSource const&) (IGXMLScanner.cpp:206)
==21268== by 0x5017E6D: xercesc_3_1::XMLScanner::scanDocument(unsigned short const*) (XMLScanner.cpp:400)
==21268== by 0x5018221: xercesc_3_1::XMLScanner::scanDocument(char const*) (XMLScanner.cpp:408)
==21268== by 0x5044F47: xercesc_3_1::SAX2XMLReaderImpl::parse(char const*) (SAX2XMLReaderImpl.cpp:451)
==21268==
==21268== LEAK SUMMARY:
==21268== definitely lost: 40 bytes in 1 blocks
==21268== indirectly lost: 12 bytes in 1 blocks
==21268== possibly lost: 0 bytes in 0 blocks
==21268== still reachable: 76,296 bytes in 8 blocks
==21268== suppressed: 0 bytes in 0 blocks
==21268== Reachable blocks (those to which a pointer was found) are not shown.
==21268== To see them, rerun with: --leak-check=full --show-leak-kinds=all
==21268==
==21268== For counts of detected and suppressed errors, rerun with: -v
==21268== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)

I've found that the leak occurs only if the following conditions are met: there is a newline character between <?xml and version="1.0" and the value of the encoding attribute is a invalid encoding name.