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errordesc.cc: Correctly append a single character to a std::string

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The idiom
    char c = ...;
    _userMsg.append( &c );
is not correct C++, because it treats the address of 'c' as a NUL-
terminated C string.  However, this is not guaranteed.

When building and testing on Debian Stretch with AddressSanitizer:
    ASAN_OPTIONS="detect_leaks=false" CXX="clang++" CC=clang CXXFLAGS="-fsanitize=address" LDFLAGS="-fsanitize=address" cmake .. -DSC_ENABLE_TESTING=ON  -DSC_BUILD_SCHEMAS="ifc2x3;ap214e3;ap209"
    ASAN_OPTIONS="detect_leaks=false" make
    ASAN_OPTIONS="detect_leaks=false" ctest . --output-on-failure
an error like the following is encountered:

==15739==ERROR: AddressSanitizer: stack-buffer-overflow on address 0x7ffeb2ca7621 at pc 0x00000043c943 bp 0x7ffeb2ca75d0 sp 0x7ffeb2ca6d80
READ of size 33 at 0x7ffeb2ca7621 thread T0
    #0 0x43c942 in __interceptor_strlen.part.45 (/home/jepler/src/stepcode/build/bin/lazy_sdai_ap214e3+0x43c942)
    #1 0x7fb9056e6143 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::append(char const*) (/usr/lib/x86_64-linux-gnu/libstdc++.so.6+0x11f143)
    #2 0x7fb905b677c3 in ErrorDescriptor::AppendToDetailMsg(char) /home/jepler/src/stepcode/src/clutils/errordesc.cc:150:5

Address 0x7ffeb2ca7621 is located in stack of thread T0 at offset 33 in frame
    #0 0x7fb905b676af in ErrorDescriptor::AppendToDetailMsg(char) /home/jepler/src/stepcode/src/clutils/errordesc.cc:149

  This frame has 1 object(s):
    [32, 33) '' <== Memory access at offset 33 overflows this variable

A similar problem with AppendToUserMsg is found by inspection.

After this change, all 200 tests pass under the AddressSanitizer
configuration
This commit is contained in:
Jeff Epler 2017-08-15 07:35:58 -05:00
parent 0d2e791e82
commit 1d01b831aa
1 changed files with 2 additions and 2 deletions
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4
src/clutils/errordesc.cc
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@ -131,7 +131,7 @@ void ErrorDescriptor::PrependToUserMsg( const char * msg ) {
}
void ErrorDescriptor::AppendToUserMsg( const char c ) {
_userMsg.append( &c );
_userMsg.push_back( c );
}
void ErrorDescriptor::AppendToUserMsg( const char * msg ) {
@ -147,7 +147,7 @@ void ErrorDescriptor::PrependToDetailMsg( const char * msg ) {
}
void ErrorDescriptor::AppendToDetailMsg( const char c ) {
_detailMsg.append( &c );
_detailMsg.push_back( c );
}
void ErrorDescriptor::AppendToDetailMsg( const char * msg ) {