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From: Dan Carpenter <dan.carpenter@oracle.com>
To: Peilin Ye <yepeilin.cs@gmail.com>
Cc: linux-usb@vger.kernel.org, Jiri Kosina <jikos@kernel.org>,
	syzkaller-bugs@googlegroups.com, linux-kernel@vger.kernel.org,
	Benjamin Tissoires <benjamin.tissoires@redhat.com>,
	linux-input@vger.kernel.org,
	linux-kernel-mentees@lists.linuxfoundation.org
Subject: Re: [Linux-kernel-mentees] [PATCH v1] usbhid: Fix slab-out-of-bounds write in hiddev_ioctl_usage()
Date: Mon, 20 Jul 2020 14:54:01 +0300	[thread overview]
Message-ID: <20200720115400.GI2549@kadam> (raw)
In-Reply-To: <20200718231218.170730-1-yepeilin.cs@gmail.com>

On Sat, Jul 18, 2020 at 07:12:18PM -0400, Peilin Ye wrote:
> `uref->usage_index` is not always being properly checked, causing
> hiddev_ioctl_usage() to go out of bounds under some cases. Fix it.
> 

Yeah.  This code is not obvious.  It doesn't come from the user directly
so we don't have to worry about nospec.  It comes from hiddev_lookup_usage()
where we set:

	uref->usage_index = j;

We know that j is less than field->maxusage but we do need to check
against field->report_count like your patch does...  The two arrays
are allocated in hid_register_field().

I don't know the code well enough to say how these arrays are used or
why the one is larger than the other so I can't give a proper
reviewed-by.  But the patch looks reasonable and doesn't introduce any
bugs which weren't there in the original code.

regards,
dan carpenter

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  reply	other threads:[~2020-07-20 11:54 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-07-18 23:12 [Linux-kernel-mentees] [PATCH v1] usbhid: Fix slab-out-of-bounds write in hiddev_ioctl_usage() Peilin Ye
2020-07-20 11:54 ` Dan Carpenter [this message]
2020-07-20 12:12   ` Dan Carpenter
2020-07-20 19:05     ` Peilin Ye
2020-07-20 19:16     ` Peilin Ye
2020-07-21  7:16       ` Dan Carpenter
2020-07-21  8:27         ` Greg Kroah-Hartman
2020-07-21  8:39           ` Dan Carpenter
2020-07-21  8:39         ` Peilin Ye
2020-07-20 19:52 ` [Linux-kernel-mentees] [PATCH v2] " Peilin Ye
2020-07-23 14:51   ` Dan Carpenter
2020-07-29 11:37 ` [Linux-kernel-mentees] [PATCH v2 RESEND] " Peilin Ye
2020-07-29 14:35   ` Dan Carpenter
2020-08-17 10:21   ` Jiri Kosina
2020-08-18 10:00     ` Peilin Ye

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