[lkml]   [2015]   [Nov]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH 4.1 11/86] iommu/amd: Fix BUG when faulting a PROT_NONE VMA
On Fri, Nov 6, 2015 at 12:49 PM, Linus Torvalds
<> wrote:
> And some "handle_mm_fault would BUG_ON()" comment is just bogus. It's
> not handle_mm_fault()'s case that you called it without checking
> proper permissions.

Side note: as to why handle_mm_fault() doesn't just do things itself,
there's a historical situation where we used to let people do things
in ptrace() that they couldn't do directly, and punch through
protections (and turn shared read-only pages into a dirty private

So the permissions checking was up to the caller, because some callers
could do things that other callers could not.

I *think* we have gotten rid of all those cases, and I guess we could
consider just making handle_mm_fault() itself stricter. But that's the
historical background on why callers need to check this.

Adding linux-mm to the cc, to see if anybody there has some comments
wrt just moving all the EFAULT handling into handle_mm_fault() and
relaxing the caller requirements.


 \ /
  Last update: 2015-11-06 22:01    [W:0.161 / U:0.024 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site