Re: One failed self test on Fedora 29

From: Jeff King <peff@peff.net>
Date: Mar 11, 2019, 03:29 UTC
Message-ID: <20190311032923.GA7087@sigill.intra.peff.net>
In-Reply-To: <CAH8yC8mg3vjPoof5SDemQ_YiL+7e1ak535U2nFnPbaWJ8xSWOA@mail.gmail.com>

On Sat, Mar 09, 2019 at 07:34:15AM -0500, Jeffrey Walton wrote:

Show 6 quoted lines

> > It would probably help to know what commit you're building.
> > The verbose test output would also be useful, e.g.:
> 
> I built with CFLAGS += -fsanitize=undefined. It looks like the
> misaligned accesses generate UBsan findings, which is causing
> t0021-conversion to fail.

You probably should use SANITIZE=undefined instead. The Makefile has some smarts to tweak build parameters based on your sanitize flag (e.g., defining NO_UNALIGNED_LOADS).

That said, I do not think sha1dc works with UBsan at this point at all. I usually do error-checking builds with:

  make SANITIZE=address,undefined BLK_SHA1=Yes

What puzzles me is not that t0021 failed, but that everything else _didn't_. Almost every script fails for me when Git is built with UBSan and sha1dc.

It would be nice to make sha1dc respect NO_UNALIGNED_LOADS. But barring that, we should probably default to BLK_SHA1 when we see SANITIZE=undefined.

-Peff