Re: Stack clash and Fedora, new kernel vulnerability, from kernel list

2017-06-21 Thread stan
On Tue, 20 Jun 2017 21:45:31 -0700 stan wrote: > On Tue, 20 Jun 2017 23:44:24 -0400 > Tony Nelson wrote: > > > It's not allocated memory. It's a Page Table Entry in the Kernel > > that ensures that no actual memory is mapped there and that the > > region is thus unreadable and unwritable. Thi

Re: Stack clash and Fedora, new kernel vulnerability, from kernel list

2017-06-20 Thread stan
On Tue, 20 Jun 2017 23:44:24 -0400 Tony Nelson wrote: > It's not allocated memory. It's a Page Table Entry in the Kernel that > ensures that no actual memory is mapped there and that the region is > thus unreadable and unwritable. This is not unlike a swapped-out > page, except the Kernel Page

Re: Stack clash and Fedora, new kernel vulnerability, from kernel list

2017-06-20 Thread Tony Nelson
On 17-06-20 13:09:50, stan wrote: On Tue, 20 Jun 2017 12:20:57 -0400 Tom Horsley wrote: > That seems like it might be impossible without architecture changes > in the chips to allow bounds checking the stack pointer in hardware > (which certainly wouldn't fix any existing systems :-). I think

Re: Stack clash and Fedora, new kernel vulnerability, from kernel list

2017-06-20 Thread stan
On Tue, 20 Jun 2017 17:08:09 +0100 Patrick O'Callaghan wrote: > Full details are in the report already cited, but briefly the fix > causes each page of the new stack frame to be probed to make sure it > doesn't overlap with the guard page (a write-protected page created to > prevent stack and hea

Re: Stack clash and Fedora, new kernel vulnerability, from kernel list

2017-06-20 Thread stan
On Tue, 20 Jun 2017 12:20:57 -0400 Tom Horsley wrote: > That seems like it might be impossible without architecture changes > in the chips to allow bounds checking the stack pointer in hardware > (which certainly wouldn't fix any existing systems :-). I think the kernel fix was the first solutio

Re: Stack clash and Fedora, new kernel vulnerability, from kernel list

2017-06-20 Thread Patrick O'Callaghan
On Tue, 2017-06-20 at 12:20 -0400, Tom Horsley wrote: > On Tue, 20 Jun 2017 08:42:39 -0700 > stan wrote: > > > My > > assumption was that this was adding the strong stack protection to the > > kernel side of things. > > That seems like it might be impossible without architecture changes > in the

Re: Stack clash and Fedora, new kernel vulnerability, from kernel list

2017-06-20 Thread Tom Horsley
On Tue, 20 Jun 2017 08:42:39 -0700 stan wrote: > My > assumption was that this was adding the strong stack protection to the > kernel side of things. That seems like it might be impossible without architecture changes in the chips to allow bounds checking the stack pointer in hardware (which cert

Re: Stack clash and Fedora, new kernel vulnerability, from kernel list

2017-06-20 Thread Patrick O'Callaghan
On Tue, 2017-06-20 at 08:42 -0700, stan wrote: > On Tue, 20 Jun 2017 13:11:24 +0100 > Patrick O'Callaghan wrote: > > > On Mon, 2017-06-19 at 23:08 -0700, stan wrote: > > > I'm running > > > the kernel with the fix, and it is working fine so far.  > > > > As I understand it (and as the bug rep

Re: Stack clash and Fedora, new kernel vulnerability, from kernel list

2017-06-20 Thread stan
On Tue, 20 Jun 2017 13:11:24 +0100 Patrick O'Callaghan wrote: > On Mon, 2017-06-19 at 23:08 -0700, stan wrote: > > I'm running > > the kernel with the fix, and it is working fine so far.  > > As I understand it (and as the bug report appears to confirm) the fix > is to ld.so, not the kernel,

Re: Stack clash and Fedora, new kernel vulnerability, from kernel list

2017-06-20 Thread Patrick O'Callaghan
On Tue, 2017-06-20 at 08:56 -0400, Tom Horsley wrote: > On Tue, 20 Jun 2017 08:32:23 -0400 > Tom Horsley wrote: > > > That doesn't make any sense. If the exploit happens in ld.so, fixing it > > doesn't do anything. All you need to do is point an executable at an > > old copy of ld.so and you have

Re: Stack clash and Fedora, new kernel vulnerability, from kernel list

2017-06-20 Thread Tom Horsley
On Tue, 20 Jun 2017 08:32:23 -0400 Tom Horsley wrote: > That doesn't make any sense. If the exploit happens in ld.so, fixing it > doesn't do anything. All you need to do is point an executable at an > old copy of ld.so and you have access to the same exploit. OK, I see it now. The exploit only ha

Re: Stack clash and Fedora, new kernel vulnerability, from kernel list

2017-06-20 Thread Tom Horsley
On Tue, 20 Jun 2017 13:11:24 +0100 Patrick O'Callaghan wrote: > As I understand it (and as the bug report appears to confirm) the fix > is to ld.so, not the kernel, though changing ld.so does of course mean > a reboot. That doesn't make any sense. If the exploit happens in ld.so, fixing it doesn'

Re: Fw: Stack clash and Fedora, new kernel vulnerability, from kernel list

2017-06-20 Thread Patrick O'Callaghan
On Mon, 2017-06-19 at 23:08 -0700, stan wrote: > I'm running > the kernel with the fix, and it is working fine so far.  As I understand it (and as the bug report appears to confirm) the fix is to ld.so, not the kernel, though changing ld.so does of course mean a reboot. How do you know it's work

Fw: Stack clash and Fedora, new kernel vulnerability, from kernel list

2017-06-19 Thread stan
I haven't seen anyone else post about this, so this message is forwarded from the kernel list, about a new kernel vulnerability. The vulnerability is severe as it leads to root authority, but so far only local logins have been demonstrated to have the ability to exploit it. So, for most Fedora use