From: Nicolas Pitre <nico@fluxnic.net>
To: Gen Zhang <blackgod016574@gmail.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: [PATCH v3] vt: Fix a missing-check bug in drivers/tty/vt/vt.c
Date: Wed, 22 May 2019 10:18:54 -0400 (EDT) [thread overview]
Message-ID: <nycvar.YSQ.7.76.1905221018170.1558@knanqh.ubzr> (raw)
In-Reply-To: <20190522121908.GA6772@zhanggen-UX430UQ>
On Wed, 22 May 2019, Gen Zhang wrote:
> In function con_init(), the pointer variable vc_cons[currcons].d, vc and
> vc->vc_screenbuf is allocated a memory space via kzalloc(). And they are
> used in the following codes.
> However, when there is a memory allocation error, kzalloc() can fail.
> Thus null pointer (vc_cons[currcons].d, vc and vc->vc_screenbuf)
> dereference may happen. And it will cause the kernel to crash. Therefore,
> we should check return value and handle the error.
> Further, since the allcoation is in a loop, we should free all the
> allocated memory in a loop.
>
> Signed-off-by: Gen Zhang <blackgod016574@gmail.com>
Reviewed-by: Nicolas Pitre <nico@fluxnic.net>
>
> ---
> diff --git a/drivers/tty/vt/vt.c b/drivers/tty/vt/vt.c
> index fdd12f8..d50f68f 100644
> --- a/drivers/tty/vt/vt.c
> +++ b/drivers/tty/vt/vt.c
> @@ -3350,10 +3350,14 @@ static int __init con_init(void)
>
> for (currcons = 0; currcons < MIN_NR_CONSOLES; currcons++) {
> vc_cons[currcons].d = vc = kzalloc(sizeof(struct vc_data), GFP_NOWAIT);
> + if (!vc)
> + goto fail1;
> INIT_WORK(&vc_cons[currcons].SAK_work, vc_SAK);
> tty_port_init(&vc->port);
> visual_init(vc, currcons, 1);
> vc->vc_screenbuf = kzalloc(vc->vc_screenbuf_size, GFP_NOWAIT);
> + if (!vc->vc_screenbuf)
> + goto fail2;
> vc_init(vc, vc->vc_rows, vc->vc_cols,
> currcons || !vc->vc_sw->con_save_screen);
> }
> @@ -3375,6 +3379,16 @@ static int __init con_init(void)
> register_console(&vt_console_driver);
> #endif
> return 0;
> +fail1:
> + while (currcons > 0) {
> + currcons--;
> + kfree(vc_cons[currcons].d->vc_screenbuf);
> +fail2:
> + kfree(vc_cons[currcons].d);
> + vc_cons[currcons].d = NULL;
> + }
> + console_unlock();
> + return -ENOMEM;
> }
> console_initcall(con_init);
>
> ---
>
next prev parent reply other threads:[~2019-05-22 14:19 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-21 2:29 [PATCH v2] vt: Fix a missing-check bug in drivers/tty/vt/vt.c Gen Zhang
2019-05-21 2:55 ` Nicolas Pitre
2019-05-21 3:09 ` Gen Zhang
2019-05-21 3:26 ` Nicolas Pitre
2019-05-21 4:00 ` Gen Zhang
2019-05-21 4:30 ` Nicolas Pitre
2019-05-21 7:39 ` Gen Zhang
2019-05-22 2:43 ` Nicolas Pitre
2019-05-22 8:10 ` Gen Zhang
2019-05-22 12:19 ` [PATCH v3] " Gen Zhang
2019-05-22 14:18 ` Nicolas Pitre [this message]
2019-05-24 2:27 ` [PATCH v3] vt: Fix a missing-check bug in con_init() Gen Zhang
2019-05-21 3:21 ` [PATCH v3] vt: Fix a missing-check bug in drivers/tty/vt/vt.c Gen Zhang
2019-05-21 6:46 ` Oleksandr Natalenko
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