From: "brian m. carlson" <sandals@crustytoothpaste.net>
To: Patrick Steinhardt <ps@pks.im>
Cc: git@vger.kernel.org
Subject: Re: [PATCH 00/11] Stop relying on SHA1 fallback for `the_hash_algo`
Date: Fri, 19 Apr 2024 19:12:59 +0000 [thread overview]
Message-ID: <ZiLCO8Wn0-4jyDdp@tapette.crustytoothpaste.net> (raw)
In-Reply-To: <cover.1713519789.git.ps@pks.im>
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On 2024-04-19 at 09:51:03, Patrick Steinhardt wrote:
> Hi,
>
> when starting up, Git will initialize `the_repository` by calling
> `initialize_the_repository()`. Part of this is also that we set the hash
> algo of `the_repository` to SHA1, which implicitly sets `the_hash_algo`
> because it is a macro expanding to `the_repository->hash_algo`.
>
> Usually, we eventually set up the correct hash algorithm here once we
> have properly set up `the_repository` via `setup_git_directory()`. But
> in some commands we actually don't require a Git repository, and thus we
> will leave the SHA1 hash algorithm in place.
>
> This has led to some subtle bugs when the context really asks for a
> SHA256 repository, which this patch series corrects for most of the
> part. Some commands need further work, like for example git-diff(1),
> where the user might want to have the ability to pick a hash function
> when run outside of a repository.
>
> Ultimately, the last patch then drops the setup of the fallback hash
> algorithm completely. This will cause `the_hash_algo` to be a `NULL`
> pointer unless explicitly configured, and thus we now start to crash
> when it gets accessed without doing so beforehand. This is a rather
> risky thing to do, but it does catch bugs where we might otherwise
> accidentally do the wrong thing. And even though I think it is the right
> thing to do even conceptually, I'd be okay to drop it if folks think
> that the risk is not worth it.
I've taken a look, and other than the minor typo I noted, this seems
fine. I'm in favour of getting rid of the SHA-1 default, even though my
gut tells me we might find a bug or two along the way where things
aren't initialized properly. I still think that'll be okay and it's
worth doing, since it'll help us prepare for the case in the future
where we want to switch the default and also for libification, where we
won't want to make those kinds of assumptions.
--
brian m. carlson (they/them or he/him)
Toronto, Ontario, CA
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next prev parent reply other threads:[~2024-04-19 19:13 UTC|newest]
Thread overview: 53+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-19 9:51 [PATCH 00/11] Stop relying on SHA1 fallback for `the_hash_algo` Patrick Steinhardt
2024-04-19 9:51 ` [PATCH 01/11] path: harden validation of HEAD with non-standard hashes Patrick Steinhardt
2024-04-19 19:03 ` brian m. carlson
2024-04-22 4:56 ` Patrick Steinhardt
2024-04-22 16:15 ` Junio C Hamano
2024-04-23 4:50 ` Patrick Steinhardt
2024-04-23 16:54 ` Junio C Hamano
2024-04-19 9:51 ` [PATCH 02/11] parse-options-cb: only abbreviate hashes when hash algo is known Patrick Steinhardt
2024-04-23 0:30 ` Justin Tobler
2024-04-19 9:51 ` [PATCH 03/11] attr: don't recompute default attribute source Patrick Steinhardt
2024-04-23 0:32 ` Justin Tobler
2024-04-19 9:51 ` [PATCH 04/11] attr: fix BUG() when parsing attrs outside of repo Patrick Steinhardt
2024-04-19 9:51 ` [PATCH 05/11] remote-curl: fix parsing of detached SHA256 heads Patrick Steinhardt
2024-04-19 9:51 ` [PATCH 06/11] builtin/rev-parse: allow shortening to more than 40 hex characters Patrick Steinhardt
2024-04-19 9:51 ` [PATCH 07/11] builtin/blame: don't access potentially unitialized `the_hash_algo` Patrick Steinhardt
2024-04-19 9:51 ` [PATCH 08/11] builtin/bundle: abort "verify" early when there is no repository Patrick Steinhardt
2024-04-19 9:51 ` [PATCH 09/11] builtin/diff: explicitly set hash algo when there is no repo Patrick Steinhardt
2024-04-22 18:41 ` Junio C Hamano
2024-04-19 9:51 ` [PATCH 10/11] builtin/shortlog: don't set up revisions without repo Patrick Steinhardt
2024-04-23 0:35 ` Justin Tobler
2024-04-19 9:51 ` [PATCH 11/11] repository: stop setting SHA1 as the default object hash Patrick Steinhardt
2024-04-19 19:12 ` brian m. carlson [this message]
2024-04-19 19:16 ` [PATCH 00/11] Stop relying on SHA1 fallback for `the_hash_algo` Junio C Hamano
2024-04-22 4:56 ` Patrick Steinhardt
2024-04-23 5:07 ` [PATCH v2 00/12] " Patrick Steinhardt
2024-04-23 5:07 ` [PATCH v2 01/12] path: harden validation of HEAD with non-standard hashes Patrick Steinhardt
2024-04-23 5:07 ` [PATCH v2 02/12] path: move `validate_headref()` to its only user Patrick Steinhardt
2024-04-23 5:07 ` [PATCH v2 03/12] parse-options-cb: only abbreviate hashes when hash algo is known Patrick Steinhardt
2024-04-23 5:07 ` [PATCH v2 04/12] attr: don't recompute default attribute source Patrick Steinhardt
2024-04-23 5:07 ` [PATCH v2 05/12] attr: fix BUG() when parsing attrs outside of repo Patrick Steinhardt
2024-04-23 5:07 ` [PATCH v2 06/12] remote-curl: fix parsing of detached SHA256 heads Patrick Steinhardt
2024-04-23 5:07 ` [PATCH v2 07/12] builtin/rev-parse: allow shortening to more than 40 hex characters Patrick Steinhardt
2024-04-23 5:08 ` [PATCH v2 08/12] builtin/blame: don't access potentially unitialized `the_hash_algo` Patrick Steinhardt
2024-04-23 5:08 ` [PATCH v2 09/12] builtin/bundle: abort "verify" early when there is no repository Patrick Steinhardt
2024-04-23 5:08 ` [PATCH v2 10/12] builtin/diff: explicitly set hash algo when there is no repo Patrick Steinhardt
2024-04-23 5:08 ` [PATCH v2 11/12] builtin/shortlog: don't set up revisions without repo Patrick Steinhardt
2024-04-23 5:08 ` [PATCH v2 12/12] repository: stop setting SHA1 as the default object hash Patrick Steinhardt
2024-04-27 22:09 ` [PATCH v2 00/12] Stop relying on SHA1 fallback for `the_hash_algo` Junio C Hamano
2024-04-29 6:05 ` Patrick Steinhardt
2024-04-29 6:34 ` [PATCH v3 00/13] " Patrick Steinhardt
2024-04-29 6:34 ` [PATCH v3 01/13] path: harden validation of HEAD with non-standard hashes Patrick Steinhardt
2024-04-29 6:34 ` [PATCH v3 02/13] path: move `validate_headref()` to its only user Patrick Steinhardt
2024-04-29 6:34 ` [PATCH v3 03/13] parse-options-cb: only abbreviate hashes when hash algo is known Patrick Steinhardt
2024-04-29 6:34 ` [PATCH v3 04/13] attr: don't recompute default attribute source Patrick Steinhardt
2024-04-29 6:34 ` [PATCH v3 05/13] attr: fix BUG() when parsing attrs outside of repo Patrick Steinhardt
2024-04-29 6:34 ` [PATCH v3 06/13] remote-curl: fix parsing of detached SHA256 heads Patrick Steinhardt
2024-04-29 6:34 ` [PATCH v3 07/13] builtin/rev-parse: allow shortening to more than 40 hex characters Patrick Steinhardt
2024-04-29 6:34 ` [PATCH v3 08/13] builtin/blame: don't access potentially unitialized `the_hash_algo` Patrick Steinhardt
2024-04-29 6:34 ` [PATCH v3 09/13] builtin/bundle: abort "verify" early when there is no repository Patrick Steinhardt
2024-04-29 6:34 ` [PATCH v3 10/13] builtin/diff: explicitly set hash algo when there is no repo Patrick Steinhardt
2024-04-29 6:35 ` [PATCH v3 11/13] builtin/shortlog: don't set up revisions without repo Patrick Steinhardt
2024-04-29 6:35 ` [PATCH v3 12/13] oss-fuzz/commit-graph: set up hash algorithm Patrick Steinhardt
2024-04-29 6:35 ` [PATCH v3 13/13] repository: stop setting SHA1 as the default object hash Patrick Steinhardt
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