Net::MailMessage: Double free if Content-Disposition header is empty

[tyler92]

Describe the bug

During the fuzzing test for Poco::Net::MailMessage ASAN reports a heap-use-after-free (which is actually double-free) issue. This happens if a parsed message is a multipart message with an empty Content-Disposition header.

To Reproduce

Poco::MemoryInputStream stream(input.data(), input.size());
Poco::Net::MailMessage mail;
mail.read(stream);

with the following input: crash-a50113a66f7c8d5530f3446b7c74a5cbc04668a2.txt

Expected behavior

The message is parsed without an error.

Logs

=================================================================
==575941==ERROR: AddressSanitizer: heap-use-after-free on address 0x515000615380 at pc 0x7fd7e5e2e9f9 bp 0x7ffc405f5e50 sp 0x7ffc405f5e48
READ of size 8 at 0x515000615380 thread T0
    #0 0x7fd7e5e2e9f8 in Poco::Net::MailMessage::~MailMessage() poco/Net/src/MailMessage.cpp:219:3
    #1 0x561b1a8ed8e3 in LLVMFuzzerTestOneInput poco/fuzzing/http_messages_fuzzer.cc:47:3
    #2 0x561b1a7f9920 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x4c920)
    #3 0x561b1a7f9095 in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool, bool*) (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x4c095)
    #4 0x561b1a7fa875 in fuzzer::Fuzzer::MutateAndTestOne() (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x4d875)
    #5 0x561b1a7fb485 in fuzzer::Fuzzer::Loop(std::vector<fuzzer::SizedFile, std::allocator<fuzzer::SizedFile>>&) (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x4e485)
    #6 0x561b1a7e95eb in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x3c5eb)
    #7 0x561b1a812622 in main (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x65622)
    #8 0x7fd7e4b82d8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16
    #9 0x7fd7e4b82e3f in __libc_start_main csu/../csu/libc-start.c:392:3
    #10 0x561b1a7dea54 in _start (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x31a54)

0x515000615380 is located 0 bytes inside of 504-byte region [0x515000615380,0x515000615578)
freed by thread T0 here:
    #0 0x561b1a8ebbbd in operator delete(void*) (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x13ebbd)
    #1 0x7fd7e5fe99b3 in Poco::Net::StringPartSource::~StringPartSource() poco/Net/src/StringPartSource.cpp:45:1
    #2 0x7fd7e5e2ea3b in Poco::Net::MailMessage::~MailMessage() poco/Net/src/MailMessage.cpp:219:3
    #3 0x561b1a8ed8e3 in LLVMFuzzerTestOneInput poco/fuzzing/http_messages_fuzzer.cc:47:3
    #4 0x561b1a7f9920 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x4c920)
    #5 0x561b1a7f9095 in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool, bool*) (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x4c095)
    #6 0x561b1a7fa875 in fuzzer::Fuzzer::MutateAndTestOne() (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x4d875)
    #7 0x561b1a7fb485 in fuzzer::Fuzzer::Loop(std::vector<fuzzer::SizedFile, std::allocator<fuzzer::SizedFile>>&) (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x4e485)
    #8 0x561b1a7e95eb in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x3c5eb)
    #9 0x561b1a812622 in main (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x65622)
    #10 0x7fd7e4b82d8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16

previously allocated by thread T0 here:
    #0 0x561b1a8eb35d in operator new(unsigned long) (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x13e35d)
    #1 0x7fd7e5e39176 in Poco::Net::MailMessage::createPartStore(std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>> const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>> const&, std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char>> const&) poco/Net/src/MailMessage.cpp:694:30
    #2 0x7fd7e5e3c197 in Poco::Net::(anonymous namespace)::MultiPartHandler::handlePart(Poco::Net::MessageHeader const&, std::istream&) poco/Net/src/MailMessage.cpp:102:30
    #3 0x7fd7e5e3731d in Poco::Net::MailMessage::handlePart(std::istream&, Poco::Net::MessageHeader const&, Poco::Net::PartHandler&) poco/Net/src/MailMessage.cpp:537:10
    #4 0x7fd7e5e332a8 in Poco::Net::MailMessage::readPart(std::istream&, Poco::Net::MessageHeader const&, Poco::Net::PartHandler&) poco/Net/src/MailMessage.cpp:514:9
    #5 0x7fd7e5e32916 in Poco::Net::MailMessage::readMultipart(std::istream&, Poco::Net::PartHandler&) poco/Net/src/MailMessage.cpp:495:3
    #6 0x7fd7e5e33be2 in Poco::Net::MailMessage::read(std::istream&) poco/Net/src/MailMessage.cpp:363:3
    #7 0x561b1a8ed8b5 in LLVMFuzzerTestOneInput poco/fuzzing/http_messages_fuzzer.cc:46:10
    #8 0x561b1a7f9920 in fuzzer::Fuzzer::ExecuteCallback(unsigned char const*, unsigned long) (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x4c920)
    #9 0x561b1a7f9095 in fuzzer::Fuzzer::RunOne(unsigned char const*, unsigned long, bool, fuzzer::InputInfo*, bool, bool*) (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x4c095)
    #10 0x561b1a7fa875 in fuzzer::Fuzzer::MutateAndTestOne() (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x4d875)
    #11 0x561b1a7fb485 in fuzzer::Fuzzer::Loop(std::vector<fuzzer::SizedFile, std::allocator<fuzzer::SizedFile>>&) (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x4e485)
    #12 0x561b1a7e95eb in fuzzer::FuzzerDriver(int*, char***, int (*)(unsigned char const*, unsigned long)) (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x3c5eb)
    #13 0x561b1a812622 in main (poco/fuzzing/prefix/bin/http_messages_fuzzer+0x65622)
    #14 0x7fd7e4b82d8f in __libc_start_call_main csu/../sysdeps/nptl/libc_start_call_main.h:58:16

SUMMARY: AddressSanitizer: heap-use-after-free poco/Net/src/MailMessage.cpp:219:3 in Poco::Net::MailMessage::~MailMessage()
Shadow bytes around the buggy address:
  0x515000615100: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x515000615180: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x515000615200: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x515000615280: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x515000615300: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
=>0x515000615380:[fd]fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x515000615400: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x515000615480: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
  0x515000615500: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fa
  0x515000615580: fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa fa
  0x515000615600: fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd fd
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
==575941==ABORTING
MS: 1 CrossOver-; base unit: 1cb911899a10687a9b6b2eb3ef9db81abcc6c10c
artifact_prefix='./'; Test unit written to ./crash-a50113a66f7c8d5530f3446b7c74a5cbc04668a2

[tyler92]

@matejk I believe it makes sense to add 'security' label here to have a clear changelog