Interestingly, the kernel code in question (C, not perl I'm afraid :-) already does this:

    while (cp > bprm->buf) {
        cp--;
        if ((*cp == ' ') || (*cp == '\t'))
            *cp = '\0';
        else
            break;
    }
[download]

i.e. it finished the executable name at the first space or tab. I guess a better patch would be to change that if test to also null out '\r' (hmm...and probably form-feed and others whilst we're at it).

I wonder how loudly people would scream if this were proposed as a kosher kernel patch. It breaks backwards compatability quite badly, but perhaps only for people who deserve it...