Re: [PATCH] selftests/mm: check strdup() and fix buf leak in parse_test_type()

["David Hildenbrand (Arm)" <david@kernel.org>]

On 8/21/26 18:09, Anshuman Tewari wrote:
> Thanks David, agreed — strdup() is overkill here for a single-use
> parse, and dropping it is the right call.
> 
> One small consideration on the approach: working on argv[0] in place
> means strsep() will overwrite the : separator with '\0', so the
> original string (e.g. "khugepaged:anon") ends up truncated after
> parsing. Nothing today reads argv[0] again afterward, so it's safe as
> things stand, but it does mean correctness quietly depends on that
> staying true — a future change that logs argv[0], re-parses it, or
> echoes it back in an error/usage message would get the mutated version
> instead of what the user actually typed.
> 
> If we'd rather not rely on that invariant, an alternative that still
> avoids strdup()/free() entirely: copy the type argument into a small
> fixed-size stack buffer (with a bounds check against its length first)
> and run strsep() on that copy instead of on argv[0] directly. Same
> benefit as your version — no allocation, nothing to free, no
> NULL-check needed — but argv[0] itself stays untouched.
> 
> Happy to write this up as a v2 if it seems worthwhile, or if you think
> relying on "nothing downstream needs argv[0]" is fine as-is, I'm okay
> going with your version too. Your call.

I don't think we have to worry about other such argv[0] users. If they ever
appear, basic testing would reveal them.

-- 
Cheers,

David