Messages in this thread | | | Date | Thu, 27 Jun 2013 14:44:17 -0400 | From | Mathieu Desnoyers <> | Subject | Re: goldfish driver: Missing get_user_pages in goldfish_pipe_read_write() |
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* Greg Kroah-Hartman (gregkh@linuxfoundation.org) wrote: > On Thu, Jun 27, 2013 at 02:03:44PM -0400, Mathieu Desnoyers wrote: > > * Greg Kroah-Hartman (gregkh@linuxfoundation.org) wrote: > > > On Thu, Jun 27, 2013 at 01:35:32PM -0400, Mathieu Desnoyers wrote: > > > > The following code snippet: > > > > > > > > drivers/platform/goldfish/goldfish_pipe.c: > > > > goldfish_pipe_read_write() > > > > > > > > /* Ensure that the corresponding page is properly mapped */ > > > > /* FIXME: this isn't safe or sufficient - use get_user_pages */ > > > > if (is_write) { > > > > char c; > > > > /* Ensure that the page is mapped and readable */ > > > > if (__get_user(c, (char __user *)address)) { > > > > if (!ret) > > > > ret = -EFAULT; > > > > break; > > > > } > > > > } else { > > > > /* Ensure that the page is mapped and writable */ > > > > if (__put_user(0, (char __user *)address)) { > > > > if (!ret) > > > > ret = -EFAULT; > > > > break; > > > > } > > > > } > > > > > > > > Seems to lack the kind of validation required to make it fail properly > > > > if the memory range is not fully populated. > > > > > > This is an emulated platform only, so it's probably not a big deal, > > > right? > > > > You're probably right. As long as it is not configured and somehow still > > accessible on a production device. > > There is no device that could ever be "production" for this emulated > hardware platform, unless a desktop system wants to "emulate" the > android userspace system somehow. Then it could be "real", but even > then, how would a user application get access to this codepath?
I think it would depend on the user access rights given to /dev/qemu_pipe. Assuming it would be only accessible by root, this would minimize the risks even more.
Thanks,
Mathieu
-- Mathieu Desnoyers EfficiOS Inc. http://www.efficios.com
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