Re: [PATCH] Input: synaptics-rmi4 - validate that the rmi_dev pointer is set before dereferencing it

[Andrew Duggan]

Hi Dmitry,

On 10/28/19 9:19 PM, Dmitry Torokhov wrote:
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> Hi Andrew,
>
> On Wed, Oct 23, 2019 at 01:24:05AM +0000, Andrew Duggan wrote:
>> A bug in hid-rmi was causing rmi_unregister_transport_device() to be
>> called even if the call to rmi_register_transport_device() failed to
>> allocate the rmi device. A patch has been submitted to fix the issue in
>> hid-rmi. This patch will ensure that should a simialr situation
>> occur then the rmi driver will not dereference a NULL pointer.
> This looks like "garbage in, garbage out" problem where we should not be
> calling unregister in the first place. I'd rather not apply this.

That's fine, like I said the actual fix to prevent 
rmi_unregister_transport_device() from being called inappropriately is 
in the hid-rmi driver.

https://lore.kernel.org/linux-input/20191023012344.20998-1-aduggan@xxxxxxxxxxxxx/

I was on the fence on whether or not it was better to prevent the NULL 
pointer dereference even at the expense of masking bugs like the one in 
the hid-rmi driver.

Thanks for the feedback,

Andrew


> Thanks.
>
> --
> Dmitry