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From: Johannes Schindelin <Johannes.Schindelin@gmx.de>
To: Junio C Hamano <gitster@pobox.com>
Cc: Elijah Newren <newren@gmail.com>,
	Elijah Newren via GitGitGadget <gitgitgadget@gmail.com>,
	Git Mailing List <git@vger.kernel.org>,
	blees@dcon.de, Kyle Meyer <kyle@kyleam.com>,
	Samuel Lijin <sxlijin@gmail.com>
Subject: Re: [PATCH v2 6/8] dir: fix checks on common prefix directory
Date: Tue, 17 Dec 2019 20:32:04 +0100 (CET)	[thread overview]
Message-ID: <nycvar.QRO.7.76.6.1912172031490.46@tvgsbejvaqbjf.bet> (raw)
In-Reply-To: <xmqqk16uj1qa.fsf@gitster-ct.c.googlers.com>

Hi Junio,

On Tue, 17 Dec 2019, Junio C Hamano wrote:

> Johannes Schindelin <Johannes.Schindelin@gmx.de> writes:
>
> >> > [XSI][Option Start]
> >> > ino_t  d_ino       File serial number.
> >> > [Option End]
> >> > char   d_name[]    Filename string of entry.
> >> >
> >> > You will notice that not even `d_type` is guaranteed.
> >>
> >> I am reasonably sure that the code (without Elijah's patches anyway)
> >> takes the possibility of missing d_type into account already.
> >>
> >> Doesn't the above mean d_name[] has to be an in-place array of some
> >> size (i.e. even a flex-array is OK)?  It does not look to me that it
> >> allows for it to be a pointer pointing at elsewhere (possibly on
> >> heap), which may be asking for trouble.
> >
> > You are right, of course.
> >
> > ...
> >
> > Is this compliant with POSIX? I guess not. Does it work? Yes, it does.
>
> I actually would not throw it into "it works" category.  The obvious
> implication is that a program like this:
>
> 	static struct dirent *fabricate(const char *name)
> 	{
>         	/* over-allocate as we do not know how long the	d_name[] is */
> 		struct dirent *ent = calloc(1, sizeof(*ent) + strlen(name) + 1);
> 		strcpy(ent->d_name, name);
> 		return ent;
> 	}
>
> 	static void show_name(const struct dirent *ent)
> 	{
> 		printf("%s\n", ent->d_name);
> 	}
>
> 	int main(int ac, char **av)
> 	{
> 		struct dirent *mine = fabricate("mine");
>                 show_name(mine);
> 		free(mine);
> 		return 0;
> 	}
>
> would be broken if you do not have d_name as an array.
>
> I would not be surprised if the segfaults you saw with Elijah's
> series all were caused by your d_name not being an array, and if
> that is the case, I'd rather see it fixed on your end than fixes
> withdrawn.

I agree with this reasoning.

Ciao,
Dscho

  reply	other threads:[~2019-12-17 19:32 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-09 20:47 [PATCH 0/8] Directory traversal bugs Elijah Newren via GitGitGadget
2019-12-09 20:47 ` [PATCH 1/8] t3011: demonstrate directory traversal failures Elijah Newren via GitGitGadget
2019-12-09 21:06   ` Denton Liu
2019-12-09 20:47 ` [PATCH 2/8] Revert "dir.c: make 'git-status --ignored' work within leading directories" Elijah Newren via GitGitGadget
2019-12-09 21:32   ` Denton Liu
2019-12-09 21:51     ` Elijah Newren
2019-12-09 22:09     ` Eric Sunshine
2019-12-09 20:47 ` [PATCH 3/8] dir: remove stray quote character in comment Elijah Newren via GitGitGadget
2019-12-09 20:47 ` [PATCH 4/8] dir: exit before wildcard fall-through if there is no wildcard Elijah Newren via GitGitGadget
2019-12-09 20:47 ` [PATCH 5/8] dir: break part of read_directory_recursive() out for reuse Elijah Newren via GitGitGadget
2019-12-09 20:47 ` [PATCH 6/8] dir: fix checks on common prefix directory Elijah Newren via GitGitGadget
2019-12-09 20:47 ` [PATCH 7/8] dir: synchronize treat_leading_path() and read_directory_recursive() Elijah Newren via GitGitGadget
2019-12-09 20:47 ` [PATCH 8/8] dir: consolidate similar code in treat_directory() Elijah Newren via GitGitGadget
2019-12-10 20:00 ` [PATCH v2 0/8] Directory traversal bugs Elijah Newren via GitGitGadget
2019-12-10 20:00   ` [PATCH v2 1/8] t3011: demonstrate directory traversal failures Elijah Newren via GitGitGadget
2019-12-10 20:00   ` [PATCH v2 2/8] Revert "dir.c: make 'git-status --ignored' work within leading directories" Elijah Newren via GitGitGadget
2019-12-10 20:00   ` [PATCH v2 3/8] dir: remove stray quote character in comment Elijah Newren via GitGitGadget
2019-12-10 20:00   ` [PATCH v2 4/8] dir: exit before wildcard fall-through if there is no wildcard Elijah Newren via GitGitGadget
2019-12-10 20:00   ` [PATCH v2 5/8] dir: break part of read_directory_recursive() out for reuse Elijah Newren via GitGitGadget
2019-12-10 20:00   ` [PATCH v2 6/8] dir: fix checks on common prefix directory Elijah Newren via GitGitGadget
2019-12-15 10:29     ` Johannes Schindelin
2019-12-16 13:51       ` Elijah Newren
2019-12-16 16:00         ` Elijah Newren
2019-12-16 18:13           ` Junio C Hamano
2019-12-16 21:08             ` Elijah Newren
2019-12-16 21:25               ` Junio C Hamano
2019-12-16 22:39                 ` Elijah Newren
2019-12-17  0:04           ` Johannes Schindelin
2019-12-17  0:14             ` Junio C Hamano
2019-12-17 11:08               ` Johannes Schindelin
2019-12-17 17:33                 ` Junio C Hamano
2019-12-17 19:32                   ` Johannes Schindelin [this message]
2019-12-17  5:26             ` Elijah Newren
2019-12-17 11:15               ` Johannes Schindelin
2019-12-17 16:58                 ` Elijah Newren
2019-12-10 20:00   ` [PATCH v2 7/8] dir: synchronize treat_leading_path() and read_directory_recursive() Elijah Newren via GitGitGadget
2019-12-10 20:00   ` [PATCH v2 8/8] dir: consolidate similar code in treat_directory() Elijah Newren via GitGitGadget
2019-12-17  8:33   ` [PATCH v3 0/3] Directory traversal bugs Elijah Newren via GitGitGadget
2019-12-17  8:33     ` [PATCH v3 1/3] t3011: demonstrate directory traversal failures Elijah Newren via GitGitGadget
2019-12-17  8:33     ` [PATCH v3 2/3] dir: remove stray quote character in comment Elijah Newren via GitGitGadget
2019-12-17  8:33     ` [PATCH v3 3/3] dir: exit before wildcard fall-through if there is no wildcard Elijah Newren via GitGitGadget
2019-12-17 11:18     ` [PATCH v3 0/3] Directory traversal bugs Johannes Schindelin
2019-12-17 18:24       ` Junio C Hamano
2019-12-21 22:05         ` Johannes Schindelin
2019-12-18 19:29     ` [PATCH v4 0/8] " Elijah Newren via GitGitGadget
2019-12-18 19:29       ` [PATCH v4 1/8] t3011: demonstrate directory traversal failures Elijah Newren via GitGitGadget
2019-12-18 19:29       ` [PATCH v4 2/8] Revert "dir.c: make 'git-status --ignored' work within leading directories" Elijah Newren via GitGitGadget
2019-12-18 19:29       ` [PATCH v4 3/8] dir: remove stray quote character in comment Elijah Newren via GitGitGadget
2019-12-18 19:29       ` [PATCH v4 4/8] dir: exit before wildcard fall-through if there is no wildcard Elijah Newren via GitGitGadget
2019-12-18 19:29       ` [PATCH v4 5/8] dir: break part of read_directory_recursive() out for reuse Elijah Newren via GitGitGadget
2019-12-18 19:29       ` [PATCH v4 6/8] dir: fix checks on common prefix directory Elijah Newren via GitGitGadget
2019-12-18 21:29         ` Junio C Hamano
2019-12-19 20:23           ` Elijah Newren
2019-12-19 22:24             ` Jeff King
2019-12-20 17:00               ` Elijah Newren
2019-12-20 21:14                 ` Jeff King
2019-12-20 18:01               ` Junio C Hamano
2019-12-20 21:15                 ` Jeff King
2019-12-18 19:29       ` [PATCH v4 7/8] dir: synchronize treat_leading_path() and read_directory_recursive() Elijah Newren via GitGitGadget
2019-12-18 19:29       ` [PATCH v4 8/8] dir: consolidate similar code in treat_directory() Elijah Newren via GitGitGadget
2019-12-19 21:28       ` [PATCH v5 0/8] Directory traversal bugs Elijah Newren via GitGitGadget
2019-12-19 21:28         ` [PATCH v5 1/8] t3011: demonstrate directory traversal failures Elijah Newren via GitGitGadget
2019-12-19 21:28         ` [PATCH v5 2/8] Revert "dir.c: make 'git-status --ignored' work within leading directories" Elijah Newren via GitGitGadget
2019-12-19 21:28         ` [PATCH v5 3/8] dir: remove stray quote character in comment Elijah Newren via GitGitGadget
2019-12-19 21:28         ` [PATCH v5 4/8] dir: exit before wildcard fall-through if there is no wildcard Elijah Newren via GitGitGadget
2019-12-19 21:28         ` [PATCH v5 5/8] dir: break part of read_directory_recursive() out for reuse Elijah Newren via GitGitGadget
2019-12-19 21:28         ` [PATCH v5 6/8] dir: fix checks on common prefix directory Elijah Newren via GitGitGadget
2019-12-19 21:28         ` [PATCH v5 7/8] dir: synchronize treat_leading_path() and read_directory_recursive() Elijah Newren via GitGitGadget
2019-12-19 21:28         ` [PATCH v5 8/8] dir: consolidate similar code in treat_directory() Elijah Newren via GitGitGadget

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