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List:       linux-kernel
Subject:    Re: [PATCH] input/vmmouse: Fix device name copies
From:       Dmitry Torokhov <dmitry.torokhov () gmail ! com>
Date:       2023-12-03 18:41:01
Message-ID: ZWzLvctpo1nNTMOo () google ! com
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Zack,

On Mon, Nov 27, 2023 at 03:42:06PM -0500, Zack Rusin wrote:
> From: Zack Rusin <zackr@vmware.com>
> 
> Make sure vmmouse_data::phys can hold serio::phys (which is 32 bytes)
> plus an extra string, extend it to 64.
> 
> Fixes gcc13 warnings:
> drivers/input/mouse/vmmouse.c: In function ‘vmmouse_init':
> drivers/input/mouse/vmmouse.c:455:53: warning: ‘/input1' directive \
> output may be truncated writing 7 bytes into a region of size between 1 \
> and 32 [-Wformat-truncation=] 455 |         snprintf(priv->phys, \
> sizeof(priv->phys), "%s/input1", |                                        \
> ^~~~~~~ drivers/input/mouse/vmmouse.c:455:9: note: ‘snprintf' output \
> between 8 and 39 bytes into a destination of size 32 455 |         \
> snprintf(priv->phys, sizeof(priv->phys), "%s/input1", |         \
> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 456 |               \
> psmouse->ps2dev.serio->phys); |                  \
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~ 
> Signed-off-by: Zack Rusin <zackr@vmware.com>
> Fixes: 8b8be51b4fd3 ("Input: add vmmouse driver")
> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
> Cc: VMware Graphics Reviewers <linux-graphics-maintainer@vmware.com>
> Cc: Arnd Bergmann <arnd@arndb.de>
> Cc: Robert Jarzmik <robert.jarzmik@free.fr>
> Cc: Raul Rangel <rrangel@chromium.org>
> Cc: linux-input@vger.kernel.org
> Cc: <stable@vger.kernel.org> # v4.1+
> ---
> drivers/input/mouse/vmmouse.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/input/mouse/vmmouse.c \
> b/drivers/input/mouse/vmmouse.c index ea9eff7c8099..7248cada4c8c 100644
> --- a/drivers/input/mouse/vmmouse.c
> +++ b/drivers/input/mouse/vmmouse.c
> @@ -72,7 +72,7 @@
> */
> struct vmmouse_data {
> 	struct input_dev *abs_dev;
> -	char phys[32];
> +	char phys[64];

This simply wastes 32 bytes. It is perfectly fine to truncate phys
(which does not happen in real life).

-Wformat-truncation is disabled in normal builds, folks should stop
using it with W=1 as well.

Thanks.

-- 
Dmitry


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