From: Marek Vasut <marex@denx.de>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH] usb: check udev before dereferencing
Date: Sat, 12 Nov 2016 19:17:23 +0100 [thread overview]
Message-ID: <a6fef258-c3ea-f06f-2f14-550ede9d8d3e@denx.de> (raw)
In-Reply-To: <20161112191028.6acc5536@crub>
On 11/12/2016 07:10 PM, Anatolij Gustschin wrote:
> On Sat, 12 Nov 2016 10:36:42 +0100
> Marek Vasut marex at denx.de wrote:
> ...
>>> udev = dev_get_parent_priv(child);
>>> + if (!udev)
>>> + continue;
>>
>> I don't quite understand the problem from the patch description, but
>> shouldn't all the return values from dev_get_parent_priv() be checked
>> this way , not just these two ?
>
> The problem is that when dereferencing NULL udev we later access
> some random address (e.g. when accessing dev->dev->parent in
> usb_show_tree_graph()). dev->dev pointer is random DRAM data there,
> when dereferencing it, data abort happens when random address
> is outside of valid address range.
I mean, I understand that udev can be NULL and we don't check it. But is
udev == NULL an expected possibility ? And if so, when does such thing
happen ?
> Probably we should check elsewhere, at least where it might
> return NULL.
OK
>>
>> Why does dev_get_parent_priv() return NULL here ?
>
> it returns NULL because the dev->parent_priv is not allocated for
> usb_mass_storage.lun0 device. I do not know the reason why.
That's probably what needs to be fixed , no ?
Also, we should most likely check all the return values of
dev_get_parent_priv() in cmd/usb.c, not just these two.
--
Best regards,
Marek Vasut
next prev parent reply other threads:[~2016-11-12 18:17 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-11-12 9:02 [U-Boot] [PATCH] usb: check udev before dereferencing Anatolij Gustschin
2016-11-12 9:36 ` Marek Vasut
2016-11-12 18:10 ` Anatolij Gustschin
2016-11-12 18:17 ` Marek Vasut [this message]
2016-11-14 20:44 ` Simon Glass
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