On 04/15, David Miller wrote:
From: Oleg Nesterov oleg@redhat.com Date: Tue, 15 Apr 2014 20:07:00 +0200
On 04/15, David Miller wrote:
From: Oleg Nesterov oleg@redhat.com Date: Tue, 15 Apr 2014 19:49:00 +0200
We do not want to write to, say, page cache if the probed application mmaps a file at the same vaddr.
If user has write access to that page... not our problem.
Well, I am not sure.
Yes, this won't allow you to write the exploit. But if this actually happens because an application is buggy, this can lead to really hard-to-debug problems.
And this is different from a stray userland scribble onto such a page how?
Sure. But I think that the kernel should not write to the file just because a buggy application did the extra munmap() or passed a wrong addres to mmap/munmap.
This is all so much simpler if you don't insist on doing all of this hand-holding for the user, that's not the kernel's job.
Well, I do not agree, but perhaps because I do not really understand what do you mean.
Oleg.