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From: Junio C Hamano <gitster@pobox.com>
To: Patrick Steinhardt <ps@pks.im>
Cc: git <git@vger.kernel.org>, Christian Couder <christian.couder@gmail.com>
Subject: Re: [PATCH 1/9] refs: fix segfault when aborting empty transaction
Date: Fri, 27 Mar 2020 12:59:25 -0700
Message-ID: <xmqqwo75fu1u.fsf@gitster.c.googlers.com> (raw)
In-Reply-To: <3c7f8c47f361c46751629b44570657ef811d94d0.1585129842.git.ps@pks.im> (Patrick Steinhardt's message of "Wed, 25 Mar 2020 10:53:28 +0100")

Patrick Steinhardt <ps@pks.im> writes:

> When cleaning up a transaction that has no updates queued, then the
> transaction's backend data will not have been allocated. We correctly
> handle this for the packed backend, where the cleanup function checks
> whether the backend data has been allocated at all -- if not, then there
> is nothing to clean up. For the files backend we do not check this and
> as a result will hit a segfault due to dereferencing a `NULL` pointer
> when cleaning up such a transaction.
>
> Fix the issue by checking whether `backend_data` is set in the files
> backend, too.
>
> Signed-off-by: Patrick Steinhardt <ps@pks.im>
> ---
>  refs/files-backend.c | 20 +++++++++++---------
>  1 file changed, 11 insertions(+), 9 deletions(-)

Makes sense.  Will queue.  Thanks.

>
> diff --git a/refs/files-backend.c b/refs/files-backend.c
> index 561c33ac8a..6516c7bc8c 100644
> --- a/refs/files-backend.c
> +++ b/refs/files-backend.c
> @@ -2565,17 +2565,19 @@ static void files_transaction_cleanup(struct files_ref_store *refs,
>  		}
>  	}
>  
> -	if (backend_data->packed_transaction &&
> -	    ref_transaction_abort(backend_data->packed_transaction, &err)) {
> -		error("error aborting transaction: %s", err.buf);
> -		strbuf_release(&err);
> +	if (backend_data) {
> +		if (backend_data->packed_transaction &&
> +		    ref_transaction_abort(backend_data->packed_transaction, &err)) {
> +			error("error aborting transaction: %s", err.buf);
> +			strbuf_release(&err);
> +		}
> +
> +		if (backend_data->packed_refs_locked)
> +			packed_refs_unlock(refs->packed_ref_store);
> +
> +		free(backend_data);
>  	}
>  
> -	if (backend_data->packed_refs_locked)
> -		packed_refs_unlock(refs->packed_ref_store);
> -
> -	free(backend_data);
> -
>  	transaction->state = REF_TRANSACTION_CLOSED;
>  }

  reply index

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-03-25  9:53 [PATCH 0/9] Support for transactions in `git-update-ref --stdin` Patrick Steinhardt
2020-03-25  9:53 ` [PATCH 1/9] refs: fix segfault when aborting empty transaction Patrick Steinhardt
2020-03-27 19:59   ` Junio C Hamano [this message]
2020-03-25  9:53 ` [PATCH 2/9] git-update-ref.txt: add missing word Patrick Steinhardt
2020-03-25  9:53 ` [PATCH 3/9] strbuf: provide function to append whole lines Patrick Steinhardt
2020-03-27 21:04   ` Junio C Hamano
2020-03-30 13:25     ` Patrick Steinhardt
2020-03-30 17:12       ` Junio C Hamano
2020-03-25  9:53 ` [PATCH 4/9] update-ref: organize commands in an array Patrick Steinhardt
2020-03-27 21:25   ` Junio C Hamano
2020-03-30  8:05     ` Patrick Steinhardt
2020-03-30 16:55       ` Junio C Hamano
2020-03-30 17:37         ` Patrick Steinhardt
2020-03-25  9:54 ` [PATCH 5/9] update-ref: drop unused argument for `parse_refname` Patrick Steinhardt
2020-03-25  9:54 ` [PATCH 6/9] update-ref: pass end pointer instead of strbuf Patrick Steinhardt
2020-03-25  9:54 ` [PATCH 7/9] update-ref: move transaction handling into `update_refs_stdin()` Patrick Steinhardt
2020-03-27 21:44   ` Junio C Hamano
2020-03-25  9:54 ` [PATCH 8/9] update-ref: read commands in a line-wise fashion Patrick Steinhardt
2020-03-27 21:58   ` Junio C Hamano
2020-03-30  8:11     ` Patrick Steinhardt
2020-03-30 17:39       ` Junio C Hamano
2020-03-25  9:54 ` [PATCH 9/9] update-ref: implement interactive transaction handling Patrick Steinhardt
2020-03-27 22:00   ` Junio C Hamano
2020-03-30 13:46 ` [PATCH v2 0/9] Support for transactions in `git-update-ref --stdin` Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 1/9] refs: fix segfault when aborting empty transaction Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 2/9] git-update-ref.txt: add missing word Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 3/9] strbuf: provide function to append whole lines Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 4/9] update-ref: organize commands in an array Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 5/9] update-ref: drop unused argument for `parse_refname` Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 6/9] update-ref: pass end pointer instead of strbuf Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 7/9] update-ref: move transaction handling into `update_refs_stdin()` Patrick Steinhardt
2020-03-30 13:46   ` [PATCH v2 8/9] update-ref: read commands in a line-wise fashion Patrick Steinhardt
2020-03-30 13:47   ` [PATCH v2 9/9] update-ref: implement interactive transaction handling Patrick Steinhardt
2020-04-02  7:09 ` [PATCH v3 0/9] Support for transactions in `git-update-ref --stdin` Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 1/9] refs: fix segfault when aborting empty transaction Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 2/9] git-update-ref.txt: add missing word Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 3/9] strbuf: provide function to append whole lines Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 4/9] update-ref: organize commands in an array Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 5/9] update-ref: drop unused argument for `parse_refname` Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 6/9] update-ref: pass end pointer instead of strbuf Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 7/9] update-ref: move transaction handling into `update_refs_stdin()` Patrick Steinhardt
2020-04-02  7:09   ` [PATCH v3 8/9] update-ref: read commands in a line-wise fashion Patrick Steinhardt
2020-04-02  7:10   ` [PATCH v3 9/9] update-ref: implement interactive transaction handling Patrick Steinhardt
2020-04-03 13:40     ` Phillip Wood
2020-04-03 16:51       ` Patrick Steinhardt
2020-04-03 17:33       ` Junio C Hamano
2020-04-03 17:35         ` Junio C Hamano
2020-04-06  7:10         ` Patrick Steinhardt

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