From: Linus Torvalds <torvalds@linux-foundation.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
"the arch/x86 maintainers" <x86@kernel.org>,
Andy Lutomirsky <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@intel.com>,
Borislav Petkov <bpetkov@suse.de>,
Greg KH <gregkh@linuxfoundation.org>,
Kees Cook <keescook@google.com>, Hugh Dickins <hughd@google.com>,
Brian Gerst <brgerst@gmail.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>,
David Laight <David.Laight@aculab.com>,
Eduardo Valentin <eduval@amazon.com>,
"Liguori, Anthony" <aliguori@amazon.com>,
Will Deacon <will.deacon@arm.com>, linux-mm <linux-mm@kvack.org>
Subject: Re: [patch 11/16] x86/ldt: Force access bit for CS/SS
Date: Tue, 12 Dec 2017 11:05:23 -0800 [thread overview]
Message-ID: <CA+55aFwzkdB7FoVcmyqBvHu2HyE+pBe_KEgN5G3KJx8ZCGW_jQ@mail.gmail.com> (raw)
In-Reply-To: <20171212173334.176469949@linutronix.de>
On Tue, Dec 12, 2017 at 9:32 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
>
> There is one exception; IRET will immediately load CS/SS and unrecoverably
> #GP. To avoid this issue access the LDT descriptors used by CS/SS before
> the IRET to userspace.
Ok, so the other patch made me nervous, this just makes me go "Hell no!".
This is exactly the kind of "now we get traps in random microcode
places that have never been tested" kind of thing that I was talking
about.
Why is the iret exception unrecoverable anyway? Does anybody even know?
Linus
WARNING: multiple messages have this Message-ID (diff)
From: Linus Torvalds <torvalds@linux-foundation.org>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: LKML <linux-kernel@vger.kernel.org>,
the arch/x86 maintainers <x86@kernel.org>,
Andy Lutomirsky <luto@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Dave Hansen <dave.hansen@intel.com>,
Borislav Petkov <bpetkov@suse.de>,
Greg KH <gregkh@linuxfoundation.org>,
Kees Cook <keescook@google.com>, Hugh Dickins <hughd@google.com>,
Brian Gerst <brgerst@gmail.com>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Denys Vlasenko <dvlasenk@redhat.com>,
Boris Ostrovsky <boris.ostrovsky@oracle.com>,
Juergen Gross <jgross@suse.com>,
David Laight <David.Laight@aculab.com>,
Eduardo Valentin <eduval@amazon.com>,
"Liguori, Anthony" <aliguori@amazon.com>,
Will Deacon <will.deacon@arm.com>, linux-mm <linux-mm@kvack.org>
Subject: Re: [patch 11/16] x86/ldt: Force access bit for CS/SS
Date: Tue, 12 Dec 2017 11:05:23 -0800 [thread overview]
Message-ID: <CA+55aFwzkdB7FoVcmyqBvHu2HyE+pBe_KEgN5G3KJx8ZCGW_jQ@mail.gmail.com> (raw)
In-Reply-To: <20171212173334.176469949@linutronix.de>
On Tue, Dec 12, 2017 at 9:32 AM, Thomas Gleixner <tglx@linutronix.de> wrote:
>
> There is one exception; IRET will immediately load CS/SS and unrecoverably
> #GP. To avoid this issue access the LDT descriptors used by CS/SS before
> the IRET to userspace.
Ok, so the other patch made me nervous, this just makes me go "Hell no!".
This is exactly the kind of "now we get traps in random microcode
places that have never been tested" kind of thing that I was talking
about.
Why is the iret exception unrecoverable anyway? Does anybody even know?
Linus
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next prev parent reply other threads:[~2017-12-12 19:05 UTC|newest]
Thread overview: 134+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-12 17:32 [patch 00/16] x86/ldt: Use a VMA based read only mapping Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 17:32 ` [patch 01/16] arch: Allow arch_dup_mmap() to fail Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 17:32 ` [patch 02/16] x86/ldt: Rework locking Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 17:32 ` [patch 03/16] x86/ldt: Prevent ldt inheritance on exec Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 17:32 ` [patch 04/16] mm/softdirty: Move VM_SOFTDIRTY into high bits Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 17:32 ` [patch 05/16] mm: Allow special mappings with user access cleared Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 18:00 ` Andy Lutomirski
2017-12-12 18:00 ` Andy Lutomirski
2017-12-12 18:05 ` Peter Zijlstra
2017-12-12 18:05 ` Peter Zijlstra
2017-12-12 18:06 ` Andy Lutomirski
2017-12-12 18:06 ` Andy Lutomirski
2017-12-12 18:25 ` Peter Zijlstra
2017-12-12 18:25 ` Peter Zijlstra
2017-12-13 12:22 ` Peter Zijlstra
2017-12-13 12:22 ` Peter Zijlstra
2017-12-13 12:57 ` Kirill A. Shutemov
2017-12-13 12:57 ` Kirill A. Shutemov
2017-12-13 14:34 ` Peter Zijlstra
2017-12-13 14:34 ` Peter Zijlstra
2017-12-13 14:43 ` Kirill A. Shutemov
2017-12-13 14:43 ` Kirill A. Shutemov
2017-12-13 15:00 ` Peter Zijlstra
2017-12-13 15:00 ` Peter Zijlstra
2017-12-13 15:04 ` Peter Zijlstra
2017-12-13 15:04 ` Peter Zijlstra
2017-12-13 15:14 ` Dave Hansen
2017-12-13 15:14 ` Dave Hansen
2017-12-13 15:32 ` Peter Zijlstra
2017-12-13 15:32 ` Peter Zijlstra
2017-12-13 15:47 ` Dave Hansen
2017-12-13 15:47 ` Dave Hansen
2017-12-13 15:54 ` Peter Zijlstra
2017-12-13 15:54 ` Peter Zijlstra
2017-12-13 18:08 ` Linus Torvalds
2017-12-13 18:08 ` Linus Torvalds
2017-12-13 18:21 ` Dave Hansen
2017-12-13 18:21 ` Dave Hansen
2017-12-13 18:23 ` Linus Torvalds
2017-12-13 18:23 ` Linus Torvalds
2017-12-13 18:31 ` Andy Lutomirski
2017-12-13 18:31 ` Andy Lutomirski
2017-12-13 18:32 ` Peter Zijlstra
2017-12-13 18:32 ` Peter Zijlstra
2017-12-13 18:35 ` Linus Torvalds
2017-12-13 18:35 ` Linus Torvalds
2017-12-14 4:53 ` Aneesh Kumar K.V
2017-12-14 4:53 ` Aneesh Kumar K.V
2017-12-13 21:50 ` Matthew Wilcox
2017-12-13 21:50 ` Matthew Wilcox
2017-12-13 22:12 ` Peter Zijlstra
2017-12-13 22:12 ` Peter Zijlstra
2017-12-14 0:10 ` Matthew Wilcox
2017-12-14 0:10 ` Matthew Wilcox
2017-12-14 0:16 ` Andy Lutomirski
2017-12-14 0:16 ` Andy Lutomirski
2017-12-12 17:32 ` [patch 06/16] mm: Provide vm_special_mapping::close Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 17:32 ` [patch 07/16] selftest/x86: Implement additional LDT selftests Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 17:32 ` [patch 08/16] selftests/x86/ldt_gdt: Prepare for access bit forced Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 17:32 ` [patch 09/16] mm: Make populate_vma_page_range() available Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 17:32 ` [patch 10/16] x86/ldt: Do not install LDT for kernel threads Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 17:57 ` Andy Lutomirski
2017-12-12 17:57 ` Andy Lutomirski
2017-12-12 17:32 ` [patch 11/16] x86/ldt: Force access bit for CS/SS Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 18:03 ` Andy Lutomirski
2017-12-12 18:03 ` Andy Lutomirski
2017-12-12 18:09 ` Peter Zijlstra
2017-12-12 18:09 ` Peter Zijlstra
2017-12-12 18:10 ` Andy Lutomirski
2017-12-12 18:10 ` Andy Lutomirski
2017-12-12 18:22 ` Andy Lutomirski
2017-12-12 18:22 ` Andy Lutomirski
2017-12-12 18:29 ` Peter Zijlstra
2017-12-12 18:29 ` Peter Zijlstra
2017-12-12 18:41 ` Thomas Gleixner
2017-12-12 18:41 ` Thomas Gleixner
2017-12-12 19:04 ` Peter Zijlstra
2017-12-12 19:04 ` Peter Zijlstra
2017-12-12 19:05 ` Linus Torvalds [this message]
2017-12-12 19:05 ` Linus Torvalds
2017-12-12 19:26 ` Andy Lutomirski
2017-12-12 19:26 ` Andy Lutomirski
2017-12-19 12:10 ` David Laight
2017-12-19 12:10 ` David Laight
2017-12-12 17:32 ` [patch 12/16] x86/ldt: Reshuffle code Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 17:32 ` [patch 13/16] x86/ldt: Introduce LDT write fault handler Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 17:58 ` Andy Lutomirski
2017-12-12 17:58 ` Andy Lutomirski
2017-12-12 18:19 ` Peter Zijlstra
2017-12-12 18:19 ` Peter Zijlstra
2017-12-12 18:43 ` Thomas Gleixner
2017-12-12 18:43 ` Thomas Gleixner
2017-12-12 19:01 ` Linus Torvalds
2017-12-12 19:01 ` Linus Torvalds
2017-12-12 19:21 ` Thomas Gleixner
2017-12-12 19:21 ` Thomas Gleixner
2017-12-12 19:51 ` Linus Torvalds
2017-12-12 19:51 ` Linus Torvalds
2017-12-12 20:21 ` Dave Hansen
2017-12-12 20:21 ` Dave Hansen
2017-12-12 20:37 ` Thomas Gleixner
2017-12-12 20:37 ` Thomas Gleixner
2017-12-12 21:35 ` Andy Lutomirski
2017-12-12 21:35 ` Andy Lutomirski
2017-12-12 21:42 ` Thomas Gleixner
2017-12-12 21:42 ` Thomas Gleixner
2017-12-12 21:41 ` Thomas Gleixner
2017-12-12 21:41 ` Thomas Gleixner
2017-12-12 21:46 ` Thomas Gleixner
2017-12-12 21:46 ` Thomas Gleixner
2017-12-12 22:25 ` Peter Zijlstra
2017-12-12 22:25 ` Peter Zijlstra
2017-12-12 17:32 ` [patch 14/16] x86/ldt: Prepare for VMA mapping Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 17:32 ` [patch 15/16] x86/ldt: Add VMA management code Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 17:32 ` [patch 16/16] x86/ldt: Make it read only VMA mapped Thomas Gleixner
2017-12-12 17:32 ` Thomas Gleixner
2017-12-12 18:03 ` [patch 00/16] x86/ldt: Use a VMA based read only mapping Andy Lutomirski
2017-12-12 18:03 ` Andy Lutomirski
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