Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-05-12 Thread H. Peter Anvin
On 05/12/2014 06:16 AM, Josh Boyer wrote: > On Wed, May 7, 2014 at 12:57 PM, Linus Torvalds > wrote: >> On Wed, May 7, 2014 at 2:18 AM, Sven Joachim wrote: >>> >>> It seems that at least some 32-bit programs are also broken, since after >>> upgrading the kernel to 3.14.3 I can no longer start my

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-05-12 Thread Josh Boyer
On Wed, May 7, 2014 at 12:57 PM, Linus Torvalds wrote: > On Wed, May 7, 2014 at 2:18 AM, Sven Joachim wrote: >> >> It seems that at least some 32-bit programs are also broken, since after >> upgrading the kernel to 3.14.3 I can no longer start my old chess >> database program: Now that this has

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-05-08 Thread H. Peter Anvin
On 05/08/2014 06:50 AM, H. Peter Anvin wrote: > Actually it could use KVM instead of CPU emulation on nearly all modern > processors... That being said, it would be cool if someone would either port the lredir backend (MFS) into Qemu, or finish the 9P front end I started writing at one point, but

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-05-08 Thread H. Peter Anvin
On 05/08/2014 06:50 AM, H. Peter Anvin wrote: > Actually it could use KVM instead of CPU emulation on nearly all modern > processors... Of course, at that point you might just run qemu-kvm instead of DOSEMU, since I seem to recall that DOSEMU is still a real version of DOS. I have to admit to mo

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-05-08 Thread H. Peter Anvin
Actually it could use KVM instead of CPU emulation on nearly all modern processors... On May 7, 2014 11:43:59 PM PDT, Sven Joachim wrote: >On 2014-05-07 19:09 +0200, H. Peter Anvin wrote: > >> On 05/07/2014 09:57 AM, Linus Torvalds wrote: >>> >>> Afaik, 16-bit programs under wine already need >

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-05-07 Thread Sven Joachim
On 2014-05-07 19:09 +0200, H. Peter Anvin wrote: > On 05/07/2014 09:57 AM, Linus Torvalds wrote: >> >> Afaik, 16-bit programs under wine already need >> >> echo 0 > /proc/sys/vm/mmap_min_addr >> >> because they want to map things at address 0, so this isn't a new concept. >> > > I think that

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-05-07 Thread Alexandre Julliard
"H. Peter Anvin" writes: > On 05/07/2014 09:57 AM, Linus Torvalds wrote: >> >> Afaik, 16-bit programs under wine already need >> >> echo 0 > /proc/sys/vm/mmap_min_addr >> >> because they want to map things at address 0, so this isn't a new concept. >> > > I think that applies to DOSEMU, but

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-05-07 Thread H. Peter Anvin
On 05/07/2014 09:57 AM, Linus Torvalds wrote: > > Afaik, 16-bit programs under wine already need > > echo 0 > /proc/sys/vm/mmap_min_addr > > because they want to map things at address 0, so this isn't a new concept. > I think that applies to DOSEMU, but not to Wine. Sven: if you have the ab

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-05-07 Thread Linus Torvalds
On Wed, May 7, 2014 at 2:18 AM, Sven Joachim wrote: > > It seems that at least some 32-bit programs are also broken, since after > upgrading the kernel to 3.14.3 I can no longer start my old chess > database program: So for backporting (and for 3.15) maybe this (TOTALLY UNTESTED) patch would be a

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-05-07 Thread Borislav Petkov
On Wed, May 07, 2014 at 11:18:49AM +0200, Sven Joachim wrote: > I would rather not set up a virtual machine just for wine (I don't > have Windows anymore). What about reactos? (I'm not saying this shouldn't be addressed, regardless...) -- Regards/Gruss, Boris. Sent from a fat crate under my

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-05-07 Thread Sven Joachim
On 2014-04-14 09:48 +0200, Alexandre Julliard wrote: > Linus Torvalds writes: > >> On Fri, Apr 11, 2014 at 11:45 AM, Brian Gerst wrote: >>> >>> I haven't tested it recently but I do know it has worked on 64-bit >>> kernels. There is no reason for it not to, the only thing not >>> supported in l

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-14 Thread H. Peter Anvin
For both of these, though, it is really kind of broken that it is a global switch, whereas typically only one application on the whole system needs it, so it would be much better to have application-specific controls. How to do that is another matter... On April 14, 2014 12:27:56 AM PDT, Ingo

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-14 Thread Ingo Molnar
* Borislav Petkov wrote: > On Mon, Apr 14, 2014 at 09:21:13AM +0200, Ingo Molnar wrote: > > Apparently the game in question is "Exile: Escape from the pit": > > > > http://osdir.com/ml/wine-bugs/2014-04/msg01159.html > > Ah, thanks. > > Well, FWIW, you can get the game for free: > > http:/

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-14 Thread Borislav Petkov
On Mon, Apr 14, 2014 at 09:21:13AM +0200, Ingo Molnar wrote: > Apparently the game in question is "Exile: Escape from the pit": > > http://osdir.com/ml/wine-bugs/2014-04/msg01159.html Ah, thanks. Well, FWIW, you can get the game for free: http://www.spiderwebsoftware.com/exile/winexile.html

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-14 Thread Alexandre Julliard
Linus Torvalds writes: > On Fri, Apr 11, 2014 at 11:45 AM, Brian Gerst wrote: >> >> I haven't tested it recently but I do know it has worked on 64-bit >> kernels. There is no reason for it not to, the only thing not >> supported in long mode is vm86. 16-bit protected mode is unchanged. > > Afa

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-14 Thread Ingo Molnar
* H. Peter Anvin wrote: > On 04/11/2014 11:41 AM, Linus Torvalds wrote: > > > > Ok, so you actually do this on x86-64, and it currently works? For > > some reason I thought that 16-bit windows apps already didn't work. > > > > Some will work, because not all 16-bit software care about the upp

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-14 Thread Ingo Molnar
* Borislav Petkov wrote: > On Sat, Apr 12, 2014 at 05:13:40PM -0400, Brian Gerst wrote: > > Performance is bad in general, running a 32-bit Fedora 20 guest. > > So this means you haven't tried the game in the guest yet, so that > we can know for sure that a guest doesn't solve your problem or

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-13 Thread Jan Janecek
2014-04-12 15:25, H. Peter Anvin: > On 04/12/2014 02:53 PM, Linus Torvalds wrote: >> On Sat, Apr 12, 2014 at 12:44 PM, H. Peter Anvin wrote: >>> Run a 32-bit VM. The 32-bit kernel does this right. >> >> I really don't think that's the answer. >> >> If people really run these 16-bit programs, we n

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread H. Peter Anvin
On 04/11/2014 02:53 PM, Andy Lutomirski wrote: > > If you want a fully correct solution, you can use a fancier allocation > policy that can fit quite a few cpus per 4G :) > The more I think about this, I think this might actually be a reasonable option, *IF* someone is willing to deal with actua

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Linus Torvalds
On Sat, Apr 12, 2014 at 7:56 PM, Andi Kleen wrote: > > Why? Either it works or it doesn't. > > If it works it doesn't make any sense to have a sysctl. BS. It "works" exactly like mmap() at NULL "works". It is a potential security leak, because x86-64 screwed up the architecture definition in th

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread H. Peter Anvin
It leaks security sensitive information to userspace and corrupts the upper half of ESP because it lacks the equivalent of the espfix workaround. On April 12, 2014 7:56:48 PM PDT, Andi Kleen wrote: >"H. Peter Anvin" writes: >> >> But yes, we can make it configurable, but the default should almo

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread H. Peter Anvin
I would think any sensible application with 16-bit segments would be using sigaltstack. Does anyone know what Wine does? On April 12, 2014 6:29:11 PM PDT, Andy Lutomirski wrote: >On Sat, Apr 12, 2014 at 6:25 PM, Andy Lutomirski >wrote: >> On Sat, Apr 12, 2014 at 5:03 PM, H. Peter Anvin >wrote

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Andi Kleen
"H. Peter Anvin" writes: > > But yes, we can make it configurable, but the default should almost > certainly be off. Why? Either it works or it doesn't. If it works it doesn't make any sense to have a sysctl. -Andi -- a...@linux.intel.com -- Speaking for myself only -- To unsubscribe from thi

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Andi Kleen
Linus Torvalds writes: > On Fri, Apr 11, 2014 at 11:27 AM, Brian Gerst wrote: >> Is this bug really still present in modern CPUs? This change breaks >> running 16-bit apps in Wine. I have a few really old games I like to >> play on occasion, and I don't have a copy of Win 3.11 to put in a VM.

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Andy Lutomirski
On Sat, Apr 12, 2014 at 6:25 PM, Andy Lutomirski wrote: > On Sat, Apr 12, 2014 at 5:03 PM, H. Peter Anvin wrote: >> A signal arriving while in the user space trampoline could seriously >> complicate life. > > Agreed. Maybe I don't agree. Have signals ever worked sensibly when delivered to a tas

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Andy Lutomirski
On Sat, Apr 12, 2014 at 5:03 PM, H. Peter Anvin wrote: >> >> No self modifying code... The far jump must be in the indirect form >> anyhow. The CS:EIP must be accessible from user mode, but not >> necessarily from compatibility mode. So the trampoline (the jump) >> and data (CS:EIP) can live prett

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread H. Peter Anvin
On 04/12/2014 04:49 PM, Alexander van Heukelum wrote: > On Sun, Apr 13, 2014, at 1:31, H. Peter Anvin wrote: > d. Trampoline in user space > > A return to the vdso with values set up in registers r8-r15 would enable > a trampoline in user space. Unfortunately there is no way >

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Alexander van Heukelum
On Sun, Apr 13, 2014, at 1:31, H. Peter Anvin wrote: > >>> d. Trampoline in user space > >>> > >>> A return to the vdso with values set up in registers r8-r15 would enable > >>> a trampoline in user space. Unfortunately there is no way > >>> to do a far JMP entirely with register state so this wou

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Alexander van Heukelum
Hi, > This is a writeup I did to a select audience before this was public: I'ld like to add an option d.2. for your consideration. Can you think of a fundamental problem with it? Greetings, Alexander > > Some workarounds I have considered: > > > > a. Using paging in a similar way to the 32

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread H. Peter Anvin
On 04/12/2014 04:26 PM, Alexander van Heukelum wrote: >>> >>> c. Trampoline in kernel space >>> >>> A trampoline in kernel space is not feasible since all ring transition >>> instructions capable of returning to 16-bit mode require the use of the >>> stack. > > "16 bit mode" -> "a mode with 16-bit

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread H. Peter Anvin
On 04/12/2014 02:53 PM, Linus Torvalds wrote: > On Sat, Apr 12, 2014 at 12:44 PM, H. Peter Anvin wrote: >> Run a 32-bit VM. The 32-bit kernel does this right. > > I really don't think that's the answer. > > If people really run these 16-bit programs, we need to allow it. > Clearly it used to wo

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Linus Torvalds
On Sat, Apr 12, 2014 at 12:44 PM, H. Peter Anvin wrote: > Run a 32-bit VM. The 32-bit kernel does this right. I really don't think that's the answer. If people really run these 16-bit programs, we need to allow it. Clearly it used to work. Just make the unconditional "don't allow 16-bit segmen

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Borislav Petkov
On Sat, Apr 12, 2014 at 05:13:40PM -0400, Brian Gerst wrote: > Performance is bad in general, running a 32-bit Fedora 20 guest. So this means you haven't tried the game in the guest yet, so that we can know for sure that a guest doesn't solve your problem or what? Btw, which game is that and can

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Brian Gerst
On Sat, Apr 12, 2014 at 4:59 PM, Borislav Petkov wrote: > On Sat, Apr 12, 2014 at 04:34:14PM -0400, Brian Gerst wrote: >> My experience with kvm so far is that is slow and clunky. It may be OK >> for a server environment, but interactively it's difficult to use. > > Are you saying, you've run your

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Borislav Petkov
On Sat, Apr 12, 2014 at 04:34:14PM -0400, Brian Gerst wrote: > My experience with kvm so far is that is slow and clunky. It may be OK > for a server environment, but interactively it's difficult to use. Are you saying, you've run your game in a guest and perf. is sucky? -- Regards/Gruss, Bor

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Brian Gerst
On Sat, Apr 12, 2014 at 4:11 PM, Borislav Petkov wrote: > On Sat, Apr 12, 2014 at 12:44:42PM -0700, H. Peter Anvin wrote: >> Run a 32-bit VM. The 32-bit kernel does this right. > > Yes, even better. > >> I suspect it would also work fine in a Qemu user mode guest (is >> this supported by KVM?), i

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Brian Gerst
For this particular game, not 16-bit in general. The installer, also 16-bit, runs perfectly. Already filed wine bug 35977. On Sat, Apr 12, 2014 at 1:18 PM, H. Peter Anvin wrote: > So Wine regressed and noone noticed? They doesn't sound like an active user > base. > > On April 11, 2014 9:44:22

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Borislav Petkov
On Sat, Apr 12, 2014 at 12:44:42PM -0700, H. Peter Anvin wrote: > Run a 32-bit VM. The 32-bit kernel does this right. Yes, even better. > I suspect it would also work fine in a Qemu user mode guest (is > this supported by KVM?), in a ReactOS VM, or some other number of > combinations. Right. S

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread H. Peter Anvin
Run a 32-bit VM. The 32-bit kernel does this right. I suspect it would also work fine in a Qemu user mode guest (is this supported by KVM?), in a ReactOS VM, or some other number of combinations. The real question is how many real users are actually affected. On April 12, 2014 12:35:41 PM PDT,

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread Borislav Petkov
On Sat, Apr 12, 2014 at 10:18:25AM -0700, H. Peter Anvin wrote: > So Wine regressed and noone noticed? They doesn't sound like an active > user base. Btw, wouldn't this obscure use case simply work in a KVM guest with a kernel <= 3.14? Because if so, we simply cut it at 3.14, everything newer has

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-12 Thread H. Peter Anvin
So Wine regressed and noone noticed? They doesn't sound like an active user base. On April 11, 2014 9:44:22 PM PDT, Brian Gerst wrote: >On Fri, Apr 11, 2014 at 2:50 PM, Linus Torvalds > wrote: >> On Fri, Apr 11, 2014 at 11:45 AM, Brian Gerst >wrote: >>> >>> I haven't tested it recently but I do

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread Brian Gerst
On Fri, Apr 11, 2014 at 2:50 PM, Linus Torvalds wrote: > On Fri, Apr 11, 2014 at 11:45 AM, Brian Gerst wrote: >> >> I haven't tested it recently but I do know it has worked on 64-bit >> kernels. There is no reason for it not to, the only thing not >> supported in long mode is vm86. 16-bit prote

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread H. Peter Anvin
On 04/11/2014 03:15 PM, Andy Lutomirski wrote: > > I just looked up my hideous code. I was doing this to test the > now-deleted int 0xcc vsyscall stuff. I used modify_ldt because either > I didn't realize that __USER32_CS was usable or I didn't think it was > ABI. Or I was just being silly. >

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread Andy Lutomirski
On Fri, Apr 11, 2014 at 2:59 PM, H. Peter Anvin wrote: > On 04/11/2014 02:53 PM, Andy Lutomirski wrote: >> >> How big of a functionality problem is it? Apparently it doesn't break >> 16-bit code on wine. >> > > It breaks *some* 16-bit code. This is actually the reason that 32 bits > has the espf

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread H. Peter Anvin
On 04/11/2014 02:53 PM, Andy Lutomirski wrote: > > How big of a functionality problem is it? Apparently it doesn't break > 16-bit code on wine. > It breaks *some* 16-bit code. This is actually the reason that 32 bits has the espfix workaround - it wasn't identified as an infoleak at the time.

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread Andy Lutomirski
On 04/11/2014 02:24 PM, H. Peter Anvin wrote: > On 04/11/2014 02:16 PM, Andy Lutomirski wrote: >> I wonder if there's an easy-ish good-enough fix: >> >> Allocate some percpu space in the fixmap. (OK, this is ugly, but >> kvmclock already does it, so it's possible.) To return to 16-bit >> userspac

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread Linus Torvalds
On Fri, Apr 11, 2014 at 2:16 PM, Andy Lutomirski wrote: > > I wonder if there's an easy-ish good-enough fix: Heh. Yes. Check the thread on lkml about three weeks ago under the subject "x86-64: Information leak: kernel stack address leaks to user space". It had exactly that as a suggestion. Anywa

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread H. Peter Anvin
On 04/11/2014 02:16 PM, Andy Lutomirski wrote: > On 04/11/2014 11:29 AM, H. Peter Anvin wrote: >> On 04/11/2014 11:27 AM, Brian Gerst wrote: >>> Is this bug really still present in modern CPUs? This change breaks >>> running 16-bit apps in Wine. I have a few really old games I like to >>> play on

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread Andy Lutomirski
On 04/11/2014 11:29 AM, H. Peter Anvin wrote: > On 04/11/2014 11:27 AM, Brian Gerst wrote: >> Is this bug really still present in modern CPUs? This change breaks >> running 16-bit apps in Wine. I have a few really old games I like to >> play on occasion, and I don't have a copy of Win 3.11 to put

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread Linus Torvalds
On Fri, Apr 11, 2014 at 11:45 AM, Brian Gerst wrote: > > I haven't tested it recently but I do know it has worked on 64-bit > kernels. There is no reason for it not to, the only thing not > supported in long mode is vm86. 16-bit protected mode is unchanged. Afaik 64-bit windows doesn't support

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread H. Peter Anvin
On 04/11/2014 11:41 AM, Linus Torvalds wrote: > > Ok, so you actually do this on x86-64, and it currently works? For > some reason I thought that 16-bit windows apps already didn't work. > Some will work, because not all 16-bit software care about the upper half of ESP getting randomly corrupted

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread Brian Gerst
On Fri, Apr 11, 2014 at 2:41 PM, Linus Torvalds wrote: > On Fri, Apr 11, 2014 at 11:27 AM, Brian Gerst wrote: >> Is this bug really still present in modern CPUs? This change breaks >> running 16-bit apps in Wine. I have a few really old games I like to >> play on occasion, and I don't have a co

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread Linus Torvalds
On Fri, Apr 11, 2014 at 11:27 AM, Brian Gerst wrote: > Is this bug really still present in modern CPUs? This change breaks > running 16-bit apps in Wine. I have a few really old games I like to > play on occasion, and I don't have a copy of Win 3.11 to put in a VM. Ok, so you actually do this o

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread Brian Gerst
On Fri, Apr 11, 2014 at 2:29 PM, H. Peter Anvin wrote: > On 04/11/2014 11:27 AM, Brian Gerst wrote: >> Is this bug really still present in modern CPUs? This change breaks >> running 16-bit apps in Wine. I have a few really old games I like to >> play on occasion, and I don't have a copy of Win 3

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread H. Peter Anvin
On 04/11/2014 11:27 AM, Brian Gerst wrote: > Is this bug really still present in modern CPUs? This change breaks > running 16-bit apps in Wine. I have a few really old games I like to > play on occasion, and I don't have a copy of Win 3.11 to put in a VM. It is not a bug, per se, but an architec

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread Brian Gerst
Is this bug really still present in modern CPUs? This change breaks running 16-bit apps in Wine. I have a few really old games I like to play on occasion, and I don't have a copy of Win 3.11 to put in a VM. On Fri, Apr 11, 2014 at 1:36 PM, tip-bot for H. Peter Anvin wrote: > Commit-ID: b3b42ac

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread H. Peter Anvin
On 04/11/2014 11:12 AM, Andy Lutomirski wrote: > > If this is what I think it is (hi, Spender), then it is probably only > useful for 3.14.y and not earlier kernels. > Not really. The kernel stack address is sensitive regardless of kASLR; in fact, it is completely orthogonal to kASLR.

Re: [tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread Andy Lutomirski
On 04/11/2014 10:36 AM, tip-bot for H. Peter Anvin wrote: > Commit-ID: b3b42ac2cbae1f3cecbb6229964a4d48af31d382 > Gitweb: http://git.kernel.org/tip/b3b42ac2cbae1f3cecbb6229964a4d48af31d382 > Author: H. Peter Anvin > AuthorDate: Sun, 16 Mar 2014 15:31:54 -0700 > Committer: H. Peter Anvin

[tip:x86/urgent] x86-64, modify_ldt: Ban 16-bit segments on 64-bit kernels

2014-04-11 Thread tip-bot for H. Peter Anvin
Commit-ID: b3b42ac2cbae1f3cecbb6229964a4d48af31d382 Gitweb: http://git.kernel.org/tip/b3b42ac2cbae1f3cecbb6229964a4d48af31d382 Author: H. Peter Anvin AuthorDate: Sun, 16 Mar 2014 15:31:54 -0700 Committer: H. Peter Anvin CommitDate: Fri, 11 Apr 2014 10:10:09 -0700 x86-64, modify_ldt: Ba