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From: Junio C Hamano <gitster@pobox•com>
To: "Phillip Wood via GitGitGadget" <gitgitgadget@gmail•com>
Cc: git@vger•kernel.org, "Derrick Stolee" <dstolee@microsoft•com>,
	"René Scharfe" <l.s.r@web•de>, "Elijah Newren" <newren@gmail•com>,
	"Johannes Schindelin" <Johannes.Schindelin@gmx•de>,
	"Phillip Wood" <phillip.wood@dunelm•org.uk>
Subject: Re: [PATCH] [RFC] sparse index: fix use-after-free bug in cache_tree_verify()
Date: Wed, 06 Oct 2021 12:17:54 -0700	[thread overview]
Message-ID: <xmqq1r4yrmhp.fsf@gitster.g> (raw)
In-Reply-To: <pull.1053.git.1633512591608.gitgitgadget@gmail.com> (Phillip Wood via GitGitGadget's message of "Wed, 06 Oct 2021 09:29:51 +0000")

"Phillip Wood via GitGitGadget" <gitgitgadget@gmail•com> writes:

/*
 * Please document what the values that can be returned from
 * this function are and what they mean, just before this
 * funciton.  I am guessing that this is "all bets are off and
 * you need to redo the computation again over the full in-core
 * index"?  It is not an error and I think it makes sense to use
 * positive 1 like this patch does instead of -1.
 */
>  
> -static void verify_one(struct repository *r,
> -		       struct index_state *istate,
> -		       struct cache_tree *it,
> -		       struct strbuf *path)
> +static int verify_one(struct repository *r,
> +		      struct index_state *istate,
> +		      struct cache_tree *it,
> +		      struct strbuf *path)
>  {



> @@ -907,6 +917,9 @@ void cache_tree_verify(struct repository *r, struct index_state *istate)
>  
>  	if (!istate->cache_tree)
>  		return;
> -	verify_one(r, istate, istate->cache_tree, &path);
> +	if (verify_one(r, istate, istate->cache_tree, &path)) {
> +		strbuf_reset(&path);
> +		verify_one(r, istate, istate->cache_tree, &path);
> +	}
>  	strbuf_release(&path);
>  }

This is just a style thing, but I would find it easier to follow if
it just recursed into itself, i.e.

-	verify_one(...);
+	if (verify_one(...))
+		cache_tree_verify(r, istate);

or

-	verify_one(...);
+	again:
+	if (verify_one(...))
+		strbuf_reset(&path);
+		goto again;
}	}

On the other hand, if the new code wants to say "I would retry at
most once, otherwise there is something wrong in me", then

> -	verify_one(r, istate, istate->cache_tree, &path);
> +	if (verify_one(r, istate, istate->cache_tree, &path)) {
> +		strbuf_reset(&path);
> +		if (verify_one(r, istate, istate->cache_tree, &path))
> +			BUG("...");
> +	}

would be better.

Other than that, nicely done.

> diff --git a/t/t1092-sparse-checkout-compatibility.sh b/t/t1092-sparse-checkout-compatibility.sh
> index 886e78715fe..85d5279b33c 100755
> --- a/t/t1092-sparse-checkout-compatibility.sh
> +++ b/t/t1092-sparse-checkout-compatibility.sh
> @@ -484,7 +484,7 @@ test_expect_success 'checkout and reset (mixed) [sparse]' '
>  test_expect_success 'merge, cherry-pick, and rebase' '
>  	init_repos &&
>  
> -	for OPERATION in "merge -m merge" cherry-pick rebase
> +	for OPERATION in "merge -m merge" cherry-pick "rebase --apply" "rebase --merge"
>  	do
>  		test_all_match git checkout -B temp update-deep &&
>  		test_all_match git $OPERATION update-folder1 &&
>
> base-commit: cefe983a320c03d7843ac78e73bd513a27806845

  parent reply	other threads:[~2021-10-06 19:18 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-10-06  9:29 [PATCH] [RFC] sparse index: fix use-after-free bug in cache_tree_verify() Phillip Wood via GitGitGadget
2021-10-06 11:20 ` Derrick Stolee
2021-10-06 14:01   ` Phillip Wood
2021-10-06 14:19     ` Derrick Stolee
2021-10-06 19:17 ` Junio C Hamano [this message]
2021-10-06 20:43   ` Derrick Stolee
2021-10-07  9:50 ` [PATCH v2] " Phillip Wood via GitGitGadget
2021-10-07 13:35   ` Derrick Stolee
2021-10-07 14:59     ` Phillip Wood
2021-10-07 13:53   ` Derrick Stolee
2021-10-07 15:05     ` Phillip Wood
2021-10-07 15:44       ` Derrick Stolee
2021-10-07 17:59         ` Phillip Wood
2021-10-07 18:07   ` [PATCH v3] " Phillip Wood via GitGitGadget
2021-10-07 21:23     ` Junio C Hamano
2021-10-08  9:09       ` Phillip Wood
2021-10-08 18:53         ` Derrick Stolee
2021-10-08 19:57         ` Junio C Hamano
2021-10-14 13:34           ` Phillip Wood
2021-10-14 16:42             ` Junio C Hamano
2021-10-08  9:38     ` Bagas Sanjaya
2021-10-14  9:40       ` Phillip Wood
2021-10-16  9:07     ` [PATCH v4] " Phillip Wood via GitGitGadget
2021-10-17  5:38       ` Junio C Hamano
2021-10-17 19:35         ` Derrick Stolee
2021-10-18  9:37         ` Phillip Wood

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