From: Junio C Hamano <gitster@pobox•com>
To: "René Scharfe" <l.s.r@web•de>
Cc: Johannes Schindelin <johannes.schindelin@gmx•de>,
git@vger•kernel.org, Stefan Beller <sbeller@google•com>,
Johannes Sixt <j6t@kdbg•org>, Jeff King <peff@peff•net>
Subject: Re: [PATCH v4 11/25] checkout: fix memory leak
Date: Mon, 08 May 2017 09:41:42 +0900 [thread overview]
Message-ID: <xmqqk25sch89.fsf@gitster.mtv.corp.google.com> (raw)
In-Reply-To: <36a581f6-077e-ca89-49d0-ad487ff222a3@web.de> ("René Scharfe"'s message of "Sat, 6 May 2017 19:14:01 +0200")
René Scharfe <l.s.r@web•de> writes:
>> /*
>> * NEEDSWORK:
>> * There is absolutely no reason to write this as a blob object
>> - * and create a phony cache entry just to leak. This hack is
>> - * primarily to get to the write_entry() machinery that massages
>> - * the contents to work-tree format and writes out which only
>> - * allows it for a cache entry. The code in write_entry() needs
>> - * to be refactored to allow us to feed a <buffer, size, mode>
>> - * instead of a cache entry. Such a refactoring would help
>> - * merge_recursive as well (it also writes the merge result to the
>> - * object database even when it may contain conflicts).
>> + * and create a phony cache entry. This hack is primarily to get
>> + * to the write_entry() machinery that massages the contents to
>> + * work-tree format and writes out which only allows it for a
>> + * cache entry. The code in write_entry() needs to be refactored
>> + * to allow us to feed a <buffer, size, mode> instead of a cache
>> + * entry. Such a refactoring would help merge_recursive as well
>> + * (it also writes the merge result to the object database even
>> + * when it may contain conflicts).
>> */
>> if (write_sha1_file(result_buf.ptr, result_buf.size,
>> blob_type, oid.hash))
>
> Random observation: Using pretend_sha1_file here would at least avoid
> writing the blob.
Yup, you should have told that to me back in Aug 2008 ;-) when I did
0cf8581e ("checkout -m: recreate merge when checking out of unmerged
index", 2008-08-30); pretend_sha1_file() was available since early
2007, and there is no excuse that this codepath did not use it.
>
>> @@ -251,6 +251,7 @@ static int checkout_merged(int pos, const struct checkout *state)
>> if (!ce)
>> die(_("make_cache_entry failed for path '%s'"), path);
>> status = checkout_entry(ce, state, NULL);
>> + free(ce);
>> return status;
>> }
>
> I wonder if that's safe. Why document a leak when it could have been
> plugged this easily instead?
>
> A leak is better than a use after free, so
> let's be extra careful here. Would it leave the index inconsistent? Or
> perhaps freeing it has become safe in the meantime?
>
> @Junio: Do you remember the reason for the leaks in 0cf8581e330
> (checkout -m: recreate merge when checking out of unmerged index).
Yes.
In the very old days it was not allowed to free(3) contents of
active_cache[] and this was an old brain fart that came out of
inertia. We are manufacturing a brand new ce, only to feed it to
checkout_entry() without even registering it to the active_cache[]
array, and the ancient rule doesn't even apply to such a case.
So I think it was safe to free(3) even back then.
> And result_buf is still leaked here, right?
Good spotting. It typically would make a larger leak than a single
ce, I would suppose ;-)
next prev parent reply other threads:[~2017-05-08 0:41 UTC|newest]
Thread overview: 178+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-26 20:19 [PATCH 00/26] Address a couple of issues identified by Coverity Johannes Schindelin
2017-04-26 20:19 ` [PATCH 01/26] mingw: avoid memory leak when splitting PATH Johannes Schindelin
2017-04-26 20:19 ` [PATCH 02/26] winansi: avoid use of uninitialized value Johannes Schindelin
2017-04-26 20:19 ` [PATCH 03/26] winansi: avoid buffer overrun Johannes Schindelin
2017-04-26 20:19 ` [PATCH 04/26] add_commit_patch_id(): avoid allocating memory unnecessarily Johannes Schindelin
2017-04-26 20:19 ` [PATCH 05/26] git_config_rename_section_in_file(): avoid resource leak Johannes Schindelin
2017-04-26 20:19 ` [PATCH 06/26] get_mail_commit_oid(): " Johannes Schindelin
2017-04-26 21:06 ` Stefan Beller
2017-04-27 5:53 ` Junio C Hamano
2017-04-28 13:39 ` Johannes Schindelin
2017-04-27 6:14 ` Johannes Sixt
2017-04-28 10:02 ` Johannes Schindelin
2017-04-26 20:19 ` [PATCH 07/26] http-backend: avoid memory leaks Johannes Schindelin
2017-04-27 6:00 ` Junio C Hamano
2017-04-28 9:40 ` Johannes Schindelin
2017-05-01 1:19 ` Junio C Hamano
2017-05-01 19:05 ` Johannes Schindelin
2017-04-26 20:19 ` [PATCH 08/26] difftool: close file descriptors after reading Johannes Schindelin
2017-04-27 6:05 ` Junio C Hamano
2017-04-28 9:51 ` Johannes Schindelin
2017-04-26 20:19 ` [PATCH 09/26] status: close file descriptor after reading git-rebase-todo Johannes Schindelin
2017-04-26 20:20 ` [PATCH 10/26] Check for EOF while parsing mails Johannes Schindelin
2017-04-27 6:07 ` Junio C Hamano
2017-04-28 9:55 ` Johannes Schindelin
2017-04-27 6:20 ` Johannes Sixt
2017-04-28 10:41 ` Johannes Schindelin
2017-04-28 11:20 ` Jeff King
2017-04-28 13:33 ` Johannes Schindelin
2017-04-28 13:45 ` Jeff King
2017-04-27 6:21 ` Jeff King
2017-04-28 10:44 ` Johannes Schindelin
2017-04-28 11:08 ` Jeff King
2017-04-28 13:37 ` Johannes Schindelin
2017-04-26 20:20 ` [PATCH 11/26] cat-file: fix memory leak Johannes Schindelin
2017-04-27 6:10 ` Junio C Hamano
2017-04-28 9:59 ` Johannes Schindelin
2017-04-26 20:20 ` [PATCH 12/26] checkout: " Johannes Schindelin
2017-04-27 6:40 ` Junio C Hamano
2017-04-28 10:51 ` Johannes Schindelin
2017-04-26 20:20 ` [PATCH 13/26] split_commit_in_progress(): " Johannes Schindelin
2017-04-26 20:20 ` [PATCH 14/26] setup_bare_git_dir(): " Johannes Schindelin
2017-04-26 21:20 ` Stefan Beller
2017-04-27 22:54 ` Johannes Schindelin
2017-04-27 6:27 ` Johannes Sixt
2017-04-27 22:57 ` Johannes Schindelin
2017-04-26 20:20 ` [PATCH 15/26] setup_discovered_git_dir(): " Johannes Schindelin
2017-04-26 20:20 ` [PATCH 16/26] pack-redundant: plug " Johannes Schindelin
2017-04-26 20:21 ` [PATCH 17/26] mktree: plug memory leaks reported by Coverity Johannes Schindelin
2017-04-26 20:21 ` [PATCH 18/26] fast-export: avoid leaking memory in handle_tag() Johannes Schindelin
2017-04-27 16:39 ` Johannes Sixt
2017-04-28 10:58 ` Johannes Schindelin
2017-04-26 20:21 ` [PATCH 19/26] receive-pack: plug memory leak in update() Johannes Schindelin
2017-04-26 20:21 ` [PATCH 20/26] line-log: avoid memory leak Johannes Schindelin
2017-04-27 17:14 ` Johannes Sixt
2017-04-28 11:02 ` Johannes Schindelin
2017-04-26 20:21 ` [PATCH 21/26] shallow: " Johannes Schindelin
2017-04-26 20:21 ` [PATCH 22/26] add_reflog_for_walk: " Johannes Schindelin
2017-04-27 17:24 ` Johannes Sixt
2017-04-28 11:33 ` Johannes Schindelin
2017-04-26 20:21 ` [PATCH 23/26] remote: plug memory leak in match_explicit() Johannes Schindelin
2017-04-26 20:21 ` [PATCH 24/26] name-rev: avoid leaking memory in the `deref` case Johannes Schindelin
2017-04-26 20:21 ` [PATCH 25/26] show_worktree(): plug memory leak Johannes Schindelin
2017-04-26 20:22 ` [PATCH 26/26] submodule_uses_worktrees(): " Johannes Schindelin
2017-04-26 21:34 ` [PATCH 00/26] Address a couple of issues identified by Coverity Stefan Beller
2017-04-27 22:50 ` Johannes Schindelin
2017-04-28 18:05 ` Stefan Beller
2017-04-28 20:29 ` Automating Coverity, was " Johannes Schindelin
2017-05-01 11:22 ` Lars Schneider
2017-05-02 11:46 ` Johannes Schindelin
2017-05-05 20:30 ` Johannes Schindelin
2017-05-10 19:48 ` Johannes Schindelin
2017-05-10 19:54 ` Stefan Beller
2017-05-11 11:33 ` Johannes Schindelin
2017-04-27 17:36 ` Johannes Sixt
2017-04-28 11:36 ` Johannes Schindelin
2017-04-28 13:49 ` [PATCH v2 00/25] " Johannes Schindelin
2017-04-28 13:49 ` [PATCH v2 01/25] mingw: avoid memory leak when splitting PATH Johannes Schindelin
2017-04-28 13:49 ` [PATCH v2 02/25] winansi: avoid use of uninitialized value Johannes Schindelin
2017-04-28 13:49 ` [PATCH v2 03/25] winansi: avoid buffer overrun Johannes Schindelin
2017-04-28 13:50 ` [PATCH v2 04/25] add_commit_patch_id(): avoid allocating memory unnecessarily Johannes Schindelin
2017-04-28 13:50 ` [PATCH v2 05/25] git_config_rename_section_in_file(): avoid resource leak Johannes Schindelin
2017-04-28 13:50 ` [PATCH v2 06/25] get_mail_commit_oid(): " Johannes Schindelin
2017-04-28 13:50 ` [PATCH v2 07/25] difftool: address a couple of resource/memory leaks Johannes Schindelin
2017-04-28 13:50 ` [PATCH v2 08/25] status: close file descriptor after reading git-rebase-todo Johannes Schindelin
2017-04-28 14:02 ` [PATCH v2 09/25] mailinfo & mailsplit: check for EOF while parsing Johannes Schindelin
2017-05-02 4:11 ` Junio C Hamano
2017-05-02 13:57 ` Johannes Schindelin
2017-04-28 14:03 ` [PATCH v2 10/25] cat-file: fix memory leak Johannes Schindelin
2017-04-28 14:03 ` [PATCH v2 11/25] checkout: " Johannes Schindelin
2017-04-28 14:03 ` [PATCH v2 12/25] split_commit_in_progress(): " Johannes Schindelin
2017-04-28 14:03 ` [PATCH v2 13/25] setup_bare_git_dir(): help static analysis Johannes Schindelin
2017-04-28 14:03 ` [PATCH v2 14/25] setup_discovered_git_dir(): " Johannes Schindelin
2017-05-02 3:57 ` Junio C Hamano
2017-05-02 12:38 ` Johannes Schindelin
2017-04-28 14:03 ` [PATCH v2 15/25] pack-redundant: plug memory leak Johannes Schindelin
2017-04-28 14:03 ` [PATCH v2 16/25] mktree: plug memory leaks reported by Coverity Johannes Schindelin
2017-04-28 14:03 ` [PATCH v2 17/25] fast-export: avoid leaking memory in handle_tag() Johannes Schindelin
2017-04-28 14:03 ` [PATCH v2 18/25] receive-pack: plug memory leak in update() Johannes Schindelin
2017-04-28 14:04 ` [PATCH v2 19/25] line-log: avoid memory leak Johannes Schindelin
2017-04-28 14:04 ` [PATCH v2 20/25] shallow: " Johannes Schindelin
2017-04-28 14:04 ` [PATCH v2 21/25] add_reflog_for_walk: " Johannes Schindelin
2017-04-28 14:04 ` [PATCH v2 22/25] remote: plug memory leak in match_explicit() Johannes Schindelin
2017-04-28 14:04 ` [PATCH v2 23/25] name-rev: avoid leaking memory in the `deref` case Johannes Schindelin
2017-05-02 3:26 ` Junio C Hamano
2017-05-02 3:42 ` Junio C Hamano
2017-05-02 14:00 ` Johannes Schindelin
2017-05-04 4:22 ` Junio C Hamano
2017-04-28 14:04 ` [PATCH v2 24/25] show_worktree(): plug memory leak Johannes Schindelin
2017-05-02 3:22 ` Junio C Hamano
2017-04-28 14:04 ` [PATCH v2 25/25] submodule_uses_worktrees(): " Johannes Schindelin
2017-05-02 3:17 ` Junio C Hamano
2017-05-02 16:00 ` [PATCH v3 00/25] Address a couple of issues identified by Coverity Johannes Schindelin
2017-05-02 16:00 ` [PATCH v3 01/25] mingw: avoid memory leak when splitting PATH Johannes Schindelin
2017-05-03 19:48 ` René Scharfe
2017-05-04 10:29 ` Johannes Schindelin
2017-05-02 16:01 ` [PATCH v3 02/25] winansi: avoid use of uninitialized value Johannes Schindelin
2017-05-03 19:48 ` René Scharfe
2017-05-04 10:23 ` Johannes Schindelin
2017-05-02 16:01 ` [PATCH v3 03/25] winansi: avoid buffer overrun Johannes Schindelin
2017-05-02 16:01 ` [PATCH v3 04/25] add_commit_patch_id(): avoid allocating memory unnecessarily Johannes Schindelin
2017-05-02 16:01 ` [PATCH v3 05/25] git_config_rename_section_in_file(): avoid resource leak Johannes Schindelin
2017-05-02 16:01 ` [PATCH v3 06/25] get_mail_commit_oid(): " Johannes Schindelin
2017-05-02 16:01 ` [PATCH v3 07/25] difftool: address a couple of resource/memory leaks Johannes Schindelin
2017-05-02 16:01 ` [PATCH v3 08/25] status: close file descriptor after reading git-rebase-todo Johannes Schindelin
2017-05-02 16:01 ` [PATCH v3 09/25] mailinfo & mailsplit: check for EOF while parsing Johannes Schindelin
2017-05-02 16:01 ` [PATCH v3 10/25] cat-file: fix memory leak Johannes Schindelin
2017-05-02 16:02 ` [PATCH v3 11/25] checkout: " Johannes Schindelin
2017-05-02 16:02 ` [PATCH v3 12/25] split_commit_in_progress(): " Johannes Schindelin
2017-05-03 20:59 ` René Scharfe
2017-05-04 10:59 ` Johannes Schindelin
2017-05-06 17:13 ` René Scharfe
2017-05-09 13:39 ` Johannes Schindelin
2017-05-02 16:02 ` [PATCH v3 13/25] setup_bare_git_dir(): help static analysis Johannes Schindelin
2017-05-02 16:02 ` [PATCH v3 14/25] setup_discovered_git_dir(): plug memory leak Johannes Schindelin
2017-05-02 17:20 ` Stefan Beller
2017-05-02 18:15 ` Jeff King
2017-05-03 9:35 ` Johannes Schindelin
2017-05-02 16:02 ` [PATCH v3 15/25] pack-redundant: " Johannes Schindelin
2017-05-02 16:02 ` [PATCH v3 16/25] mktree: plug memory leaks reported by Coverity Johannes Schindelin
2017-05-02 16:02 ` [PATCH v3 17/25] fast-export: avoid leaking memory in handle_tag() Johannes Schindelin
2017-05-02 16:02 ` [PATCH v3 18/25] receive-pack: plug memory leak in update() Johannes Schindelin
2017-05-02 16:02 ` [PATCH v3 19/25] line-log: avoid memory leak Johannes Schindelin
2017-05-02 16:02 ` [PATCH v3 20/25] shallow: " Johannes Schindelin
2017-05-02 16:02 ` [PATCH v3 21/25] add_reflog_for_walk: " Johannes Schindelin
2017-05-02 16:02 ` [PATCH v3 22/25] remote: plug memory leak in match_explicit() Johannes Schindelin
2017-05-02 16:02 ` [PATCH v3 23/25] name-rev: avoid leaking memory in the `deref` case Johannes Schindelin
2017-05-02 16:03 ` [PATCH v3 24/25] show_worktree(): plug memory leak Johannes Schindelin
2017-05-02 16:03 ` [PATCH v3 25/25] submodule_uses_worktrees(): " Johannes Schindelin
2017-05-04 13:54 ` [PATCH v4 00/25] Address a couple of issues identified by Coverity Johannes Schindelin
2017-05-04 13:55 ` [PATCH v4 01/25] mingw: avoid memory leak when splitting PATH Johannes Schindelin
2017-05-04 13:55 ` [PATCH v4 02/25] winansi: avoid use of uninitialized value Johannes Schindelin
2017-05-04 13:55 ` [PATCH v4 03/25] winansi: avoid buffer overrun Johannes Schindelin
2017-05-04 13:55 ` [PATCH v4 04/25] add_commit_patch_id(): avoid allocating memory unnecessarily Johannes Schindelin
2017-05-04 13:55 ` [PATCH v4 05/25] git_config_rename_section_in_file(): avoid resource leak Johannes Schindelin
2017-05-04 13:55 ` [PATCH v4 06/25] get_mail_commit_oid(): " Johannes Schindelin
2017-05-04 13:55 ` [PATCH v4 07/25] difftool: address a couple of resource/memory leaks Johannes Schindelin
2017-05-04 13:55 ` [PATCH v4 08/25] status: close file descriptor after reading git-rebase-todo Johannes Schindelin
2017-05-04 13:56 ` [PATCH v4 09/25] mailinfo & mailsplit: check for EOF while parsing Johannes Schindelin
2017-05-04 13:56 ` [PATCH v4 10/25] cat-file: fix memory leak Johannes Schindelin
2017-05-04 13:56 ` [PATCH v4 11/25] checkout: " Johannes Schindelin
2017-05-06 17:14 ` René Scharfe
2017-05-08 0:41 ` Junio C Hamano [this message]
2017-05-09 13:42 ` Johannes Schindelin
2017-05-09 22:51 ` Junio C Hamano
2017-05-04 13:56 ` [PATCH v4 12/25] split_commit_in_progress(): simplify & " Johannes Schindelin
2017-05-04 13:56 ` [PATCH v4 13/25] setup_bare_git_dir(): help static analysis Johannes Schindelin
2017-05-04 13:56 ` [PATCH v4 14/25] setup_discovered_git_dir(): plug memory leak Johannes Schindelin
2017-05-04 13:56 ` [PATCH v4 15/25] pack-redundant: " Johannes Schindelin
2017-05-04 13:57 ` [PATCH v4 16/25] mktree: plug memory leaks reported by Coverity Johannes Schindelin
2017-05-04 13:57 ` [PATCH v4 17/25] fast-export: avoid leaking memory in handle_tag() Johannes Schindelin
2017-05-04 13:57 ` [PATCH v4 18/25] receive-pack: plug memory leak in update() Johannes Schindelin
2017-05-04 13:58 ` [PATCH v4 19/25] line-log: avoid memory leak Johannes Schindelin
2017-05-04 13:58 ` [PATCH v4 20/25] shallow: " Johannes Schindelin
2017-05-04 13:58 ` [PATCH v4 21/25] add_reflog_for_walk: " Johannes Schindelin
2017-05-04 13:59 ` [PATCH v4 22/25] remote: plug memory leak in match_explicit() Johannes Schindelin
2017-05-04 13:59 ` [PATCH v4 23/25] name-rev: avoid leaking memory in the `deref` case Johannes Schindelin
2017-05-04 13:59 ` [PATCH v4 24/25] show_worktree(): plug memory leak Johannes Schindelin
2017-05-04 13:59 ` [PATCH v4 25/25] submodule_uses_worktrees(): " Johannes Schindelin
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