Re: Accessing user-land memory without safe functions

Scotty Bauer
2015-12-04T00:32:31Z

Hi Jon,

Thanks for the response.

Here is one such example, although benign due to the
function being called with CAP_SYS_ADMIN. I'll work on patches for some of the
other issues and send those soon as well.

https://lkml.org/lkml/2015/12/1/566

On 12/03/2015 05:12 PM, Jonathan Corbet wrote:
> On Thu, 3 Dec 2015 13:54:30 -0700
> Scotty Bauer <sbauer@eng.utah.edu> wrote:
>
>> Since I've seen this a couple times now I'm wondering if my
>> understanding of touching user-land memory is flawed.
>>
>> For the above example Ioctl, the proper way to get access to those fields
>> through the safe copy_from_user or get_user() functions, correct?
>>
>> I'm wondering if I should submit patches to fix the issues I've found,
>> but now I'm doubting whether they're really issues at all.
>
> They sound like bugs to me, though it would be easier to say for sure with
> a pointer to a specific function in the kernel source. Please point
> something out, or, perhaps better, send a patch fixing one of them.
>
> Thanks,
>
> jon
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