From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from cloud.peff.net (cloud.peff.net [104.130.231.41]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D62A92CCB7 for ; Tue, 11 Jun 2024 09:12:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=104.130.231.41 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718097171; cv=none; b=ndYXRKtbXAFm1YvyOHVYjryRSXqIJ1xw5FI/5CTt2ebUux8kF02ILdSMDySqdnB3NjNVHPpqOuuiQfns5qpPM8hFEktR7B5aVSIvbZ8QOd9lRDQtJDFjWZtIWl1HcjvdbSNG6ZBaIWE0vUT8WD6BXbFTTLx1rG8a8mzxkjoPOgA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1718097171; c=relaxed/simple; bh=9Q4++Fd0Qp+UU5xjuDKjXWmYSTN9nh73Cb+x7K+3/Ps=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qUzWc1aFd/uLTuXcHH92Ngm5vOlI0KIlF4t1SmNoGAe8EU2y8S1RLhcO+rLvEM8HrqyHqDFhHTf2DlCKOg9oRbbG0wM+zBf7k7MPBD5NvhlmZJgw4Ek9kyiQJn+wyJdk/6aCcBppFAeNFN/HTOAI0Xo+X3dqRxt8D9XLDhScwco= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=peff.net; spf=pass smtp.mailfrom=peff.net; arc=none smtp.client-ip=104.130.231.41 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=peff.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=peff.net Received: (qmail 18799 invoked by uid 109); 11 Jun 2024 09:12:49 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with ESMTP; Tue, 11 Jun 2024 09:12:49 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 25103 invoked by uid 111); 11 Jun 2024 09:12:46 -0000 Received: from coredump.intra.peff.net (HELO coredump.intra.peff.net) (10.0.0.2) by peff.net (qpsmtpd/0.94) with (TLS_AES_256_GCM_SHA384 encrypted) ESMTPS; Tue, 11 Jun 2024 05:12:46 -0400 Authentication-Results: peff.net; auth=none Date: Tue, 11 Jun 2024 05:12:48 -0400 From: Jeff King To: Taylor Blau Cc: Junio C Hamano , Kyle Lippincott , Git Mailing List Subject: Re: MSan failures in pack-bitmap Message-ID: <20240611091248.GA3264564@coredump.intra.peff.net> References: <20240608081855.GA2390433@coredump.intra.peff.net> <20240611080220.GG3248245@coredump.intra.peff.net> Precedence: bulk X-Mailing-List: git@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240611080220.GG3248245@coredump.intra.peff.net> On Tue, Jun 11, 2024 at 04:02:20AM -0400, Jeff King wrote: > > So in short, I think the fix I posted above should be tracked down to > > 'maint' at least for the 2.45.x series. It will avoid the MSan failures > > and more importantly the issue I described above. I would also like to > > find a way to further test this case so that we aren't bit by such a bug > > in the future. > > I don't think we can test the case where the bug would produce a bogus > pack, since that implies guessing the uninitialized data. I guess we > could come up with a case where try_partial_reuse() should say "this is > OK to reuse", but the bogus pack_int_id prevents it. Which implies > looking at the resulting pack and checking that some delta is there that > we expect? Ah, never mind. I see you worked up a test in the v2 patches you sent. -Peff