[lkml]   [2021]   [Aug]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v2 1/3] x86/mce: Avoid infinite loop for copy from user recovery
On Fri, Aug 20, 2021 at 09:51:41PM -0700, Tony Luck wrote:
> On Fri, Aug 20, 2021 at 1:25 PM Luck, Tony <> wrote:
> > Probably the same for the two different addresses case ... though I'm
> > not 100% confident about that. There could be some ioctl() that peeks
> > at two parts of a passed in structure, and the user might pass in a
> > structure that spans across a page boundary with both pages poisoned.
> > But that would only hit if the driver code ignored the failure of the
> > first get_user() and blindly tried the second. So I'd count that as a
> > critically bad driver bug.
> Or maybe driver writers are just evil :-(
> for (i = 0; i < len; i++) {
> tx_wait(10);
> get_user([1], bin++);
> get_user([2], bin++);
> get_user([3], bin++);
> }

Almost any unchecked get_user()/put_user() is a bug. Fortunately, there's
not a lot of them
93 for put_user() and 73 for get_user(). _Some_ of the former variety might
be legitimate, but most should be taken out and shot.

And dsp56k should be taken out and shot, period ;-/ This is far from the
worst in there...

 \ /
  Last update: 2021-08-21 23:52    [W:0.080 / U:0.184 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site