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Date:   Mon, 27 Jul 2020 18:04:56 -0400
From:   Peilin Ye <yepeilin.cs@gmail.com>
To:     Dan Carpenter <dan.carpenter@oracle.com>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Sakari Ailus <sakari.ailus@linux.intel.com>,
        Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
        Vandana BN <bnvandana@gmail.com>,
        Ezequiel Garcia <ezequiel@collabora.com>,
        Niklas =?iso-8859-1?Q?S=F6derlund?= 
        <niklas.soderlund+renesas@ragnatech.se>,
        linux-kernel-mentees@lists.linuxfoundation.org,
        Linux Media Mailing List <linux-media@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [Linux-kernel-mentees] [PATCH v3] media/v4l2-core: Fix
 kernel-infoleak in video_put_user()
Message-ID: <20200727220456.GA328887@PWN>
References: <20200726220557.102300-1-yepeilin.cs@gmail.com>
 <20200726222703.102701-1-yepeilin.cs@gmail.com>
 <CAK8P3a3NB2BVo9fH-Wcinrhhs-QJ=9dK59Ds83TvgLmEkRy3qA@mail.gmail.com>
 <20200727131608.GD1913@kadam>
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On Mon, Jul 27, 2020 at 04:16:08PM +0300, Dan Carpenter wrote:
> drivers/char/hpet.c:675 hpet_ioctl() warn: check that 'info' doesn't leak information (struct has a hole after 'hi_timer')

This one seems like a false positive.

drivers/char/hpet.c:670:

	mutex_lock(&hpet_mutex);
	err = hpet_ioctl_common(file->private_data, cmd, arg, &info);
	mutex_unlock(&hpet_mutex);

	if ((cmd == HPET_INFO) && !err &&
	    (copy_to_user((void __user *)arg, &info, sizeof(info))))
		err = -EFAULT;

`info` is only being copied to userspace when `cmd` is `HPET_INFO`.
However, hpet_ioctl_common() is already doing memset() on `info` in
`case HPET_INFO`:

drivers/char/hpet.c:612:

	case HPET_INFO:
		{
			memset(info, 0, sizeof(*info));
			^^^^^^

Thank you,
Peilin Ye