Language: C
Label: vulnerable
CWE: CWE-120 \u2014 Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')
The product copies an input buffer to an output buffer without verifying that the size of the input buffer is less than the size of the output buffer, leading to a buffer overflow.

Code:
test_custom_handler(void **state)
{
    (void) state;

    /*
     * Test registering a custom handler
     */
    TSS2_RC_HANDLER old = Tss2_RC_SetHandler(1, "cstm", custom_err_handler);
    assert_null(old);

    /*
     * Test getting error strings
     */
    unsigned i;
    for (i = 1; i < 4; i++) {
        // Make a layer 1 error with an error number of i.
        TSS2_RC rc = TSS2_RC_LAYER(1) | i;
        char buf[256];
        snprintf(buf, sizeof(buf), "cstm:error %u", i);

        const char *e = Tss2_RC_Decode(rc);
        assert_string_equal(e, buf);
    }

    TSS2_RC rc = TSS2_RC_LAYER(1) | 42;

    /*
     * Test an unknown error
     */
    const char *e = Tss2_RC_Decode(rc);
    assert_string_equal(e, "cstm:0x2A");

    /*
     * Test clearing a handler
     */
    old = Tss2_RC_SetHandler(1, "cstm", NULL);
    assert_ptr_equal(old, custom_err_handler);

    /*
     * Test an unknown layer
     */
    e = Tss2_RC_Decode(rc);
    assert_string_equal(e, "1:0x2A");
}