From: Sam Ravnborg <sam@ravnborg.org>
To: Nicolas Pitre <nico@fluxnic.net>
Cc: gregkh@linuxfoundation.org, jslaby@suse.com,
daniel.vetter@ffwll.ch, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] vt: fix unicode console freeing with a common interface
Date: Sat, 2 May 2020 17:57:29 +0200 [thread overview]
Message-ID: <20200502155729.GA12824@ravnborg.org> (raw)
In-Reply-To: <nycvar.YSQ.7.76.2005021043110.2671@knanqh.ubzr>
Hi Nicolas
On Sat, May 02, 2020 at 11:01:07AM -0400, Nicolas Pitre wrote:
> By directly using kfree() in different places we risk missing one if
> it is switched to using vfree(), especially if the corresponding
> vmalloc() is hidden away within a common abstraction.
>
> Oh wait, that's exactly what happened here.
>
> So let's fix this by creating a common abstraction for the free case
> as well.
>
> Signed-off-by: Nicolas Pitre <nico@fluxnic.net>
> Reported-by: syzbot+0bfda3ade1ee9288a1be@syzkaller.appspotmail.com
> Fixes: 9a98e7a80f95 ("vt: don't use kmalloc() for the unicode screen buffer")
> Cc: <stable@vger.kernel.org>
Looks good.
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Not the I know the code, but verified that no more kfree() was
used for vc_uni_screen.
Sam
>
> diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
> index e5ffed795e..48a8199f78 100644
> --- a/drivers/tty/vt/vt.c
> +++ b/drivers/tty/vt/vt.c
> @@ -365,9 +365,14 @@ static struct uni_screen *vc_uniscr_alloc(unsigned int cols, unsigned int rows)
> return uniscr;
> }
>
> +static void vc_uniscr_free(struct uni_screen *uniscr)
> +{
> + vfree(uniscr);
> +}
> +
> static void vc_uniscr_set(struct vc_data *vc, struct uni_screen *new_uniscr)
> {
> - vfree(vc->vc_uni_screen);
> + vc_uniscr_free(vc->vc_uni_screen);
> vc->vc_uni_screen = new_uniscr;
> }
>
> @@ -1230,7 +1235,7 @@ static int vc_do_resize(struct tty_struct *tty, struct vc_data *vc,
> err = resize_screen(vc, new_cols, new_rows, user);
> if (err) {
> kfree(newscreen);
> - kfree(new_uniscr);
> + vc_uniscr_free(new_uniscr);
> return err;
> }
>
prev parent reply other threads:[~2020-05-02 15:57 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-02 15:01 [PATCH] vt: fix unicode console freeing with a common interface Nicolas Pitre
2020-05-02 15:57 ` Sam Ravnborg [this message]
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