Messages in this thread | | | Subject | Re: copy_from_user/copy_to_user question | From | Steven Rostedt <> | Date | Sat, 03 Dec 2005 07:14:45 -0500 |
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On Sat, 2005-12-03 at 10:43 +0100, Heiko Carstens wrote: > > > > > Secondly, they seem to use memcpy as opposed to using > > > > > copy_to_user/copy_from_user which is also very > > > > > dangerous. > > > > > > > > If they are grabbing data from user context into kernel (or vise versa) > > > > that could easily cause an oops. Not to mention it is a security risk. > > > > > > Not to mention it simply won't work on a many platforms, no matter what... > > > > Hmm, I've only worked with a few platforms (i386, x86_64, ppc, mips, and > > a little arm but I don't remember that much). I believe that a memcpy > > could work on all these platforms (error prone of course, but if the > > memory is mapped its OK). When entering a system call, the kernel still > > has access to the memory locations assigned to the user. > > Won't work at all on platforms that have distinct address spaces for user > and kernel space. E.g. on s390/s390x it wouldn't work. And yes, there are > special instructions to copy data between address spaces.
Thanks for the update. That's why I love working in an open environment. You learn something new every day ;)
-- Steve
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