gistfile1.txt

    printf("memcpy userlen %d bytes into msg %d bytes, from offset %d\n",
           data->userlen, len, (((char *) &(msg->val)) - ((char *) msg)));
    memcpy (msg->val, data->name, (size_t) data->userlen);





memcpy userlen 8 bytes into msg 20 bytes, from offset 12
=================================================================
==26838==ERROR: AddressSanitizer: negative-size-param: (size=8)
    #0 0x7fe75a315d91 in __asan_memcpy /build/gcc/src/gcc-5.3.0/libsanitizer/asan/asan_interceptors.cc:367
    #1 0x401c51 in peer_send_peer_information src/4c-server.c:260
    #2 0x401d0d in handle_registration src/4c-server.c:285
    #3 0x40157c in handle_msg src/4c-server.c:71
    #4 0x4016f6 in handle_connection src/4c-server.c:137
    #5 0x7fe75a0734a3 in start_thread (/usr/lib/libpthread.so.0+0x74a3)
    #6 0x7fe7599a613c in clone (/usr/lib/libc.so.6+0xe913c)

==26838==AddressSanitizer CHECK failed: /build/gcc/src/gcc-5.3.0/libsanitizer/asan/asan_report.cc:322 "((0 && "Address is not in memory and not in shadow?")) != (0)" (0x0, 0x0)
    #0 0x7fe75a329951 in AsanCheckFailed /build/gcc/src/gcc-5.3.0/libsanitizer/asan/asan_rtl.cc:68
    #1 0x7fe75a32e903 in __sanitizer::CheckFailed(char const*, int, char const*, unsigned long long, unsigned long long) /build/gcc/src/gcc-5.3.0/libsanitizer/sanitizer_common/sanitizer_common.cc:72
    #2 0x7fe75a325ea7 in __asan::DescribeAddressIfShadow(unsigned long, __asan::AddressDescription*, bool) /build/gcc/src/gcc-5.3.0/libsanitizer/asan/asan_report.cc:322
    #3 0x7fe75a326f97 in __asan::DescribeAddress(unsigned long, unsigned long) /build/gcc/src/gcc-5.3.0/libsanitizer/asan/asan_report.cc:550
    #4 0x7fe75a3280cf in __asan::ReportStringFunctionSizeOverflow(unsigned long, unsigned long, __sanitizer::BufferedStackTrace*) /build/gcc/src/gcc-5.3.0/libsanitizer/asan/asan_report.cc:817
    #5 0x7fe75a315e05 in __asan_memcpy /build/gcc/src/gcc-5.3.0/libsanitizer/asan/asan_interceptors.cc:367
    #6 0x401c51 in peer_send_peer_information src/4c-server.c:260
    #7 0x401d0d in handle_registration src/4c-server.c:285
    #8 0x40157c in handle_msg src/4c-server.c:71
    #9 0x4016f6 in handle_connection src/4c-server.c:137
    #10 0x7fe75a0734a3 in start_thread (/usr/lib/libpthread.so.0+0x74a3)
    #11 0x7fe7599a613c in clone (/usr/lib/libc.so.6+0xe913c)