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From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Richard Weinberger <richard@nod.at>
Cc: uml-devel <user-mode-linux-devel@lists.sourceforge.net>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [uml-devel] [PATCH 07/15] hostfs: Remove open coded strcpy()
Date: Mon, 16 Mar 2015 13:03:03 +0100	[thread overview]
Message-ID: <CAMuHMdXpkyvoTRYZ5X4dVNKoHA=seiYpS7pFSZc+fzxFRM=r2Q@mail.gmail.com> (raw)
In-Reply-To: <1426506079-26183-8-git-send-email-richard@nod.at>

On Mon, Mar 16, 2015 at 12:41 PM, Richard Weinberger <richard@nod.at> wrote:
> --- a/fs/hostfs/hostfs_kern.c
> +++ b/fs/hostfs/hostfs_kern.c
> @@ -105,11 +105,10 @@ static char *__dentry_name(struct dentry *dentry, char *name)

This code looks fishy to me...

First we have:

    len = strlen(root);
    strlcpy(name, root, PATH_MAX);

(I notice the code used strncpy() before. One difference with strlcpy()
 is that strncpy() fills the remaining of the destination buffer with zeroes.)

Then:

>                 __putname(name);
>                 return NULL;
>         }
> -       if (p > name + len) {
> -               char *s = name + len;

Unless strlcpy() truncated the string (which is unlikely, as root
cannot be longer
than PATH_MAX?), s = name + len now points to the zero terminator.
So the below would copy just one single byte:

> -               while ((*s++ = *p++) != '\0')
> -                       ;
> -       }
> +
> +       if (p > name + len)
> +               strcpy(name + len, p);
> +

What is this code really supposed to do?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds

  reply	other threads:[~2015-03-16 12:03 UTC|newest]

Thread overview: 19+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-03-16 11:41 Hostfs updates Richard Weinberger
2015-03-16 11:41 ` [PATCH 01/15] hostfs: hostfs_file_open: Switch to data locking model Richard Weinberger
2015-03-16 11:41 ` [PATCH 02/15] hostfs: hostfs_file_open: Fix a fd leak in hostfs_file_open Richard Weinberger
2015-03-16 11:41 ` [PATCH 03/15] hostfs: Allow fsync on directories Richard Weinberger
2015-03-16 11:41 ` [PATCH 04/15] hostfs: Handle bogus st.mode Richard Weinberger
2015-03-16 11:41 ` [PATCH 05/15] hostfs: Make hostfs_readpage more readable Richard Weinberger
2015-03-16 11:41 ` [PATCH 06/15] hostfs: Add a BUG_ON to detect behavior changes of dentry_path_raw() Richard Weinberger
2015-03-16 11:41 ` [PATCH 07/15] hostfs: Remove open coded strcpy() Richard Weinberger
2015-03-16 12:03   ` Geert Uytterhoeven [this message]
2015-03-16 12:18     ` [uml-devel] " Richard Weinberger
2015-03-16 12:44       ` Geert Uytterhoeven
2015-03-16 11:41 ` [PATCH 08/15] hostfs: Use __getname() in follow_link Richard Weinberger
2015-03-16 11:41 ` [PATCH 09/15] hostfs: Report append flag in ->show_options() Richard Weinberger
2015-03-16 11:41 ` [PATCH 10/15] hostfs: Remove superfluous test in hostfs_open() Richard Weinberger
2015-03-16 11:41 ` [PATCH 11/15] hostfs: hostfs_open: Reset open flags upon each retry Richard Weinberger
2015-03-16 11:41 ` [PATCH 12/15] hostfs: Remove superfluous initializations in hostfs_open() Richard Weinberger
2015-03-16 11:41 ` [PATCH 13/15] hostfs: Set page flags in hostfs_readpage() correctly Richard Weinberger
2015-03-16 11:41 ` [PATCH 14/15] hostfs: Use page_offset() Richard Weinberger
2015-03-16 11:41 ` [PATCH 15/15] hostfs: No need to box and later unbox the file mode Richard Weinberger

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