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From: Jeff King <peff@peff.net>
To: Teng Long <dyroneteng@gmail.com>
Cc: avarab@gmail.com, git@vger.kernel.org, gitster@pobox.com,
	sunshine@sunshineco.com, tenglong.tl@alibaba-inc.com
Subject: Re: [PATCH v10 4/6] notes.c: introduce '[--[no-]separator|--separator=<paragraph-break>]' option
Date: Thu, 18 May 2023 20:54:47 -0400	[thread overview]
Message-ID: <20230519005447.GA2955320@coredump.intra.peff.net> (raw)
In-Reply-To: <820dda0458994fdf7ff37870736ce6ed7871720c.1684411136.git.dyroneteng@gmail.com>

On Thu, May 18, 2023 at 08:02:09PM +0800, Teng Long wrote:

> +static void insert_separator(struct strbuf *message, size_t pos)
> +{
> +	if (!separator)
> +		return;
> +	else if (separator[strlen(separator) - 1] == '\n')
> +		strbuf_insertstr(message, pos, separator);
> +	else
> +		strbuf_insertf(message, pos, "%s%s", separator, "\n");
> +}

This function causes UBSan to complain on 'next' (though curiously only
with clang, not with gcc[1]). The version in next seems to be from your
v9, but it's largely the same except for the "if (!separator)"
condition.

The problem is in the middle condition here. If "separator" is non-NULL,
but is an empty string, then strlen() will return 0, and we will look at
the out-of-bounds byte just before the string.

We'd probably want something like this:

diff --git a/builtin/notes.c b/builtin/notes.c
index 3215bce19b..a46d6dac5c 100644
--- a/builtin/notes.c
+++ b/builtin/notes.c
@@ -231,7 +231,8 @@ static void write_note_data(struct note_data *d, struct object_id *oid)
 
 static void insert_separator(struct strbuf *message, size_t pos)
 {
-	if (separator[strlen(separator) - 1] == '\n')
+	size_t sep_len = strlen(separator);
+	if (sep_len && separator[sep_len - 1] == '\n')
 		strbuf_addstr(message, separator);
 	else
 		strbuf_insertf(message, pos, "%s%s", separator, "\n");

to fix it, though I am not 100% clear on what is supposed to happen for
an empty separator here.

I was also confused that applying the fix on top of the culprit in
'next', 3993a53a13 (notes.c: introduce '--separator=<paragraph-break>'
option, 2023-04-28), still leads to test failures in t3301. But I think
that is independent of this fix. It fails even without my patch above
(and without UBSan) in test 66, "append: specify separator with line
break". But the failure goes away in the following patch, ad3d1f8feb
(notes.c: append separator instead of insert by pos, 2023-04-28).

I haven't been following this series enough to know what's going on, but
you may want to figure out where the failure is coming from in
3993a53a13. If the change in ad3d1f8feb is merely papering over it, then
we'd need to find and fix the true cause. If the bug is really fixed by
ad3d1f8feb, we might want to squash those two together to avoid broken
bisections.

-Peff

[1] To reproduce, I did:

      git checkout 3993a53a13
      make SANITIZE=address,undefined CC=clang
      cd t && ./t3301-notes.sh -v -i

    I'm using clang-14 on a Debian machine.

  parent reply	other threads:[~2023-05-19  0:55 UTC|newest]

Thread overview: 186+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-10-13  5:56 [RFC PATCH 0/2] notes.c: introduce "--no-blankline" option Teng Long
2022-10-13  5:56 ` [RFC PATCH 1/2] " Teng Long
2022-10-13  6:06   ` Junio C Hamano
2022-10-17 13:19     ` Teng Long
2022-10-13  9:31   ` Ævar Arnfjörð Bjarmason
2022-10-17 13:33     ` Teng Long
2022-10-13  5:56 ` [RFC PATCH 2/2] notes.c: fixed tip when target and append note are both empty Teng Long
2022-10-13  9:36   ` Ævar Arnfjörð Bjarmason
2022-10-13 10:10     ` Phillip Wood
2022-10-13 10:23       ` Ævar Arnfjörð Bjarmason
2022-10-15 19:40         ` Phillip Wood
2022-10-18  3:25       ` Teng Long
2022-10-18  8:08       ` Teng Long
2022-10-18  3:11     ` Teng Long
2022-10-18  9:23       ` Ævar Arnfjörð Bjarmason
2022-11-07 13:57 ` [PATCH v2 0/3] notes.c: introduce "--blank-line" option Teng Long
2022-11-07 13:57   ` [PATCH v2 1/3] " Teng Long
2022-11-07 14:45     ` Ævar Arnfjörð Bjarmason
2022-11-07 15:45       ` Eric Sunshine
2022-11-07 17:22         ` Ævar Arnfjörð Bjarmason
2022-11-07 21:46           ` Taylor Blau
2022-11-07 22:36             ` Ævar Arnfjörð Bjarmason
2022-11-08  0:32               ` Taylor Blau
2022-11-08  3:45       ` Teng Long
2022-11-08 13:06       ` Teng Long
2022-11-08 13:22         ` Ævar Arnfjörð Bjarmason
2022-11-09  6:35           ` Teng Long
2022-11-07 15:06     ` Ævar Arnfjörð Bjarmason
2022-11-08  6:32       ` Teng Long
2022-11-07 21:47     ` Taylor Blau
2022-11-08  7:36       ` Teng Long
2022-11-07 13:57   ` [PATCH v2 2/3] notes.c: fixed tip when target and append note are both empty Teng Long
2022-11-07 14:40     ` Ævar Arnfjörð Bjarmason
2022-11-07 21:51       ` Taylor Blau
2022-11-07 22:33         ` Ævar Arnfjörð Bjarmason
2022-11-07 22:45           ` Taylor Blau
2022-11-08  8:55           ` Teng Long
2022-11-07 13:57   ` [PATCH v2 3/3] notes.c: drop unreachable code in "append_edit()" Teng Long
2022-11-07 14:41     ` Ævar Arnfjörð Bjarmason
2022-11-07 14:57   ` [PATCH v2 0/3] notes.c: introduce "--blank-line" option Ævar Arnfjörð Bjarmason
2022-11-09  7:05     ` Teng Long
2022-11-09  7:06     ` Teng Long
2022-11-09  9:06   ` [PATCH v3 0/5] notes.c: introduce "--no-blank-line" option Teng Long
2022-11-09  9:06     ` [PATCH v3 1/5] notes.c: cleanup 'strbuf_grow' call in 'append_edit' Teng Long
2022-11-09  9:06     ` [PATCH v3 2/5] notes.c: cleanup for "designated init" and "char ptr init" Teng Long
2022-11-09  9:06     ` [PATCH v3 3/5] notes.c: drop unreachable code in 'append_edit()' Teng Long
2022-11-09  9:06     ` [PATCH v3 4/5] notes.c: provide tips when target and append note are both empty Teng Long
2022-11-09  9:06     ` [PATCH v3 5/5] notes.c: introduce "--no-blank-line" option Teng Long
2022-11-28 14:20     ` [PATCH v3 0/5] " Teng Long
2022-11-29  1:10       ` Junio C Hamano
2022-11-29 22:53         ` Taylor Blau
2022-11-29 12:57     ` Teng Long
2022-11-29 13:19       ` Junio C Hamano
2022-12-15 12:48         ` Teng Long
2022-12-19  3:03           ` Eric Sunshine
2022-12-21  9:16             ` Teng Long
2022-12-21 11:35               ` Junio C Hamano
2022-12-22  9:30             ` Teng Long
2022-12-23  1:36               ` Eric Sunshine
2023-01-12  2:48     ` [PATCH v4 0/5] notes.c: introduce "--separator" optio Teng Long
2023-01-12  2:48       ` [PATCH v4 1/5] notes.c: cleanup 'strbuf_grow' call in 'append_edit' Teng Long
2023-01-15  4:53         ` Eric Sunshine
2023-01-28 11:22           ` Teng Long
2023-01-12  2:48       ` [PATCH v4 2/5] notes.c: cleanup for "designated init" and "char ptr init" Teng Long
2023-01-12  9:51         ` Ævar Arnfjörð Bjarmason
2023-01-28 11:33           ` Teng Long
2023-01-12  2:48       ` [PATCH v4 3/5] notes.c: drop unreachable code in 'append_edit()' Teng Long
2023-01-15 20:59         ` Eric Sunshine
2023-01-15 21:10           ` Eric Sunshine
2023-01-28 11:50           ` Teng Long
2023-01-30  5:38             ` Eric Sunshine
2023-02-01  8:08               ` Teng Long
2023-01-12  2:48       ` [PATCH v4 4/5] notes.c: provide tips when target and append note are both empty Teng Long
2023-01-12  9:52         ` Ævar Arnfjörð Bjarmason
2023-01-15 21:28         ` Eric Sunshine
2023-01-12  2:48       ` [PATCH v4 5/5] notes.c: introduce "--separator" option Teng Long
2023-01-12  9:53         ` Ævar Arnfjörð Bjarmason
2023-01-15 22:04           ` Eric Sunshine
2023-01-15 22:15         ` Eric Sunshine
2023-02-16 13:05       ` [PATCH v5 0/3] " Teng Long
2023-02-16 13:05         ` [PATCH v5 1/3] notes.c: cleanup 'strbuf_grow' call in 'append_edit' Teng Long
2023-02-16 18:39           ` Junio C Hamano
2023-02-20  3:34             ` Teng Long
2023-02-16 13:05         ` [PATCH v5 2/3] notes.c: cleanup for "designated init" Teng Long
2023-02-16 18:39           ` Junio C Hamano
2023-02-16 13:05         ` [PATCH v5 3/3] notes.c: introduce "--separator" option Teng Long
2023-02-16 23:22           ` Junio C Hamano
2023-02-20 14:00             ` Teng Long
2023-02-21 21:31               ` Junio C Hamano
2023-02-22  8:17                 ` Teng Long
2023-02-22 23:15                   ` Junio C Hamano
2023-02-23  7:29         ` [PATCH v6 0/3] " Teng Long
2023-02-23  7:29           ` [PATCH v6 1/3] notes.c: cleanup 'strbuf_grow' call in 'append_edit' Teng Long
2023-02-23  7:29           ` [PATCH v6 2/3] notes.c: cleanup for "designated init" Teng Long
2023-02-23  7:29           ` [PATCH v6 3/3] notes.c: introduce '--separator=<paragraph-break>' option Teng Long
2023-02-23 18:21             ` Junio C Hamano
2023-02-28 14:11               ` Teng Long
2023-02-25 21:30             ` Junio C Hamano
2023-02-28 14:14               ` Teng Long
2023-03-27 13:13           ` [PATCH v6 0/3] notes.c: introduce "--separator" option Teng Long
2023-03-28 14:28           ` [PATCH v7 0/4] " Teng Long
2023-03-28 14:28             ` [PATCH v7 1/4] notes.c: cleanup 'strbuf_grow' call in 'append_edit' Teng Long
2023-03-28 14:28             ` [PATCH v7 2/4] notes.c: cleanup for "designated init" Teng Long
2023-03-29 22:17               ` Junio C Hamano
2023-03-28 14:28             ` [PATCH v7 3/4] notes.c: introduce '--separator=<paragraph-break>' option Teng Long
2023-03-28 15:37               ` Junio C Hamano
2023-03-29 14:15                 ` Teng Long
2023-03-29 21:48                   ` Junio C Hamano
2023-04-13  9:36                     ` Teng Long
2023-03-28 14:28             ` [PATCH v7 4/4] notes.c: don't do stripespace when parse file arg Teng Long
2023-03-28 15:54               ` Junio C Hamano
2023-03-29 12:06                 ` Teng Long
2023-03-29 16:21                   ` Junio C Hamano
2023-04-25 13:34             ` [PATCH 0/6] notes.c: introduce "--separator" option Teng Long
2023-04-25 13:34               ` [PATCH v8 1/6] notes.c: cleanup 'strbuf_grow' call in 'append_edit' Teng Long
2023-04-25 13:34               ` [PATCH v8 2/6] notes.c: use designated initializers for clarity Teng Long
2023-04-25 13:34               ` [PATCH v8 3/6] t3321: add test cases about the notes stripspace behavior Teng Long
2023-04-25 16:25                 ` Junio C Hamano
2023-04-27  3:47                   ` Teng Long
2023-04-25 13:34               ` [PATCH v8 4/6] notes.c: introduce '--separator=<paragraph-break>' option Teng Long
2023-04-25 17:34                 ` Junio C Hamano
2023-04-27  7:21                   ` Teng Long
2023-04-27 18:21                     ` Junio C Hamano
2023-04-25 17:35                 ` Junio C Hamano
2023-04-25 13:34               ` [PATCH v8 5/6] notes.c: append separator instead of insert by pos Teng Long
2023-04-25 17:47                 ` Junio C Hamano
2023-04-27  7:51                   ` Teng Long
2023-04-25 13:34               ` [PATCH v8 6/6] notes.c: introduce "--[no-]stripspace" option Teng Long
2023-04-25 17:49                 ` Junio C Hamano
2023-04-28  7:40                   ` Teng Long
2023-04-28 18:21                     ` Junio C Hamano
2023-04-28  9:23               ` [PATCH v9 0/6] notes.c: introduce "--separator" option Teng Long
2023-04-28  9:23                 ` [PATCH v9 1/6] notes.c: cleanup 'strbuf_grow' call in 'append_edit' Teng Long
2023-04-28  9:23                 ` [PATCH v9 2/6] notes.c: use designated initializers for clarity Teng Long
2023-04-28  9:23                 ` [PATCH v9 3/6] t3321: add test cases about the notes stripspace behavior Teng Long
2023-04-28  9:23                 ` [PATCH v9 4/6] notes.c: introduce '--separator=<paragraph-break>' option Teng Long
2023-04-28 20:44                   ` Junio C Hamano
2023-05-06  9:12                     ` Teng Long
2023-05-06  9:22                       ` Teng Long
2023-05-10 19:19                   ` Kristoffer Haugsbakk
2023-05-12  4:07                     ` Teng Long
2023-05-12  7:29                       ` Kristoffer Haugsbakk
2023-05-16 17:00                       ` Junio C Hamano
2023-05-17  3:58                         ` Teng Long
2023-05-17 15:32                           ` Junio C Hamano
2023-06-14  1:02                   ` Junio C Hamano
2023-06-14  1:10                     ` [PATCH] notes: do not access before the beginning of an array Junio C Hamano
2023-06-14  1:41                     ` [PATCH v9 4/6] notes.c: introduce '--separator=<paragraph-break>' option Eric Sunshine
2023-06-14  2:07                       ` Junio C Hamano
2023-06-15  7:13                         ` Jeff King
2023-06-15 19:15                           ` Junio C Hamano
2023-06-19  6:08                             ` Teng Long
2023-06-20 20:36                               ` Junio C Hamano
2023-06-21  2:50                                 ` Teng Long
2023-04-28  9:23                 ` [PATCH v9 5/6] notes.c: append separator instead of insert by pos Teng Long
2023-04-28  9:23                 ` [PATCH v9 6/6] notes.c: introduce "--[no-]stripspace" option Teng Long
2023-04-28 20:46                 ` [PATCH v9 0/6] notes.c: introduce "--separator" option Junio C Hamano
2023-05-01 22:29                 ` Junio C Hamano
2023-05-18 12:02                 ` [PATCH v10 " Teng Long
2023-05-18 12:02                   ` [PATCH v10 1/6] notes.c: cleanup 'strbuf_grow' call in 'append_edit' Teng Long
2023-05-18 12:02                   ` [PATCH v10 2/6] notes.c: use designated initializers for clarity Teng Long
2023-05-18 12:02                   ` [PATCH v10 3/6] t3321: add test cases about the notes stripspace behavior Teng Long
2023-05-18 12:02                   ` [PATCH v10 4/6] notes.c: introduce '[--[no-]separator|--separator=<paragraph-break>]' option Teng Long
2023-05-18 14:34                     ` Kristoffer Haugsbakk
2023-05-20 10:41                       ` Teng Long
2023-05-20 16:12                         ` Kristoffer Haugsbakk
2023-05-19  0:54                     ` Jeff King [this message]
2023-05-27  7:17                       ` Teng Long
2023-05-27 17:19                         ` Jeff King
2023-05-29 11:48                           ` Teng Long
2023-05-18 12:02                   ` [PATCH v10 5/6] notes.c: append separator instead of insert by pos Teng Long
2023-05-18 12:02                   ` [PATCH v10 6/6] notes.c: introduce "--[no-]stripspace" option Teng Long
2023-05-18 13:56                   ` [PATCH v10 0/6] notes.c: introduce "--separator" option Kristoffer Haugsbakk
2023-05-20 10:22                     ` Teng Long
2023-05-18 15:17                   ` Junio C Hamano
2023-05-20 10:59                     ` Teng Long
2023-05-27  7:57                   ` [PATCH v11 0/7] notes.c: introduce "--separator" Teng Long
2023-05-27  7:57                     ` [PATCH v11 1/7] notes.c: cleanup 'strbuf_grow' call in 'append_edit' Teng Long
2023-05-27  7:57                     ` [PATCH v11 2/7] notes.c: use designated initializers for clarity Teng Long
2023-05-27  7:57                     ` [PATCH v11 3/7] t3321: add test cases about the notes stripspace behavior Teng Long
2023-05-27  7:57                     ` [PATCH v11 4/7] notes.c: introduce '--separator=<paragraph-break>' option Teng Long
2023-05-27  7:57                     ` [PATCH v11 5/7] notes.c: append separator instead of insert by pos Teng Long
2023-05-27  7:57                     ` [PATCH v11 6/7] notes.c: introduce "--[no-]stripspace" option Teng Long
2023-05-27  7:57                     ` [PATCH v11 7/7] notes: introduce "--no-separator" option Teng Long
2023-06-01  5:50                     ` [PATCH v11 0/7] notes.c: introduce "--separator" Junio C Hamano
2023-06-03 10:01                       ` Teng Long

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