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From: Wolfram Sang <wsa@the-dreams.de>
To: Alexander Popov <alex.popov@linux.com>
Cc: "Uwe Kleine-König" <u.kleine-koenig@pengutronix.de>,
	linux-i2c@vger.kernel.org, linux-kernel@vger.kernel.org,
	sil2review@lists.osadl.org, "Dmitry Vyukov" <dvyukov@google.com>,
	syzkaller@googlegroups.com
Subject: Re: [v2 1/1] i2c: dev: prevent ZERO_SIZE_PTR deref in i2cdev_ioctl_rdwr()
Date: Fri, 27 Apr 2018 14:06:58 +0200	[thread overview]
Message-ID: <20180427120658.wi32f7margtfazzp@ninjato> (raw)
In-Reply-To: <1524140962-25639-1-git-send-email-alex.popov@linux.com>

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On Thu, Apr 19, 2018 at 03:29:22PM +0300, Alexander Popov wrote:
> i2cdev_ioctl_rdwr() allocates i2c_msg.buf using memdup_user(), which
> returns ZERO_SIZE_PTR if i2c_msg.len is zero.
> 
> Currently i2cdev_ioctl_rdwr() always dereferences the buf pointer in case
> of I2C_M_RD | I2C_M_RECV_LEN transfer. That causes a kernel oops in
> case of zero len.
> 
> Let's check the len against zero before dereferencing buf pointer.
> 
> This issue was triggered by syzkaller.
> 
> Signed-off-by: Alexander Popov <alex.popov@linux.com>

Applied to for-current with the arithmetic expression changed to '< 1'
to keep in sync with the previous one. Will push out soon, so you can
double check if you are interested.

Thanks for the debugging, Alexander!


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  parent reply	other threads:[~2018-04-27 12:07 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-04-19 12:29 [v2 1/1] i2c: dev: prevent ZERO_SIZE_PTR deref in i2cdev_ioctl_rdwr() Alexander Popov
2018-04-19 13:49 ` Uwe Kleine-König
2018-04-19 17:01   ` Alexander Popov
2018-04-20  5:58     ` Uwe Kleine-König
2018-04-23 20:18   ` Alexander Popov
2018-04-27 12:06 ` Wolfram Sang [this message]
2018-04-30  7:13   ` Uwe Kleine-König

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