Error: strncat-param-overlap

Address Sanitizer Error: strncat-param-overlap

Code that moves memory in overlapping buffer can cause hard-to-diagnose errors.

Example

This example shows how AddressSanitizer can catch errors caused by overlapped parameters to CRT functions.

(Based on llvm-project/compiler-rt/test/asan/TestCases/strncat-overlap.cpp.)

// example1.cpp
// strncat-param-overlap error
#include <string.h>

void bad_function() {
    char buffer[] = "hello\0XXX";
    strncat(buffer, buffer + 1, 3); // BOOM
    return;
}

int main(int argc, char **argv) {
    bad_function();
    return 0;
}

To build and test this example, run these commands in a Visual Studio 2019 version 16.9 or later developer command prompt:

cl example1.cpp /fsanitize=address /Zi
devenv /debugexe example1.exe

Resulting error

See also

AddressSanitizer overview
AddressSanitizer known issues
AddressSanitizer build and language reference
AddressSanitizer runtime reference
AddressSanitizer shadow bytes
AddressSanitizer cloud or distributed testing
AddressSanitizer debugger integration
AddressSanitizer error examples