Re: [Stable-review] [22/45] KVM: Fix fs/gs reload oops with invalid ldt

Re: [Stable-review] [22/45] KVM: Fix fs/gs reload oops with invalid ldt

[Ben Hutchings]

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Greg KH <gregkh@suse.de> wrote:
> 2.6.32-stable review patch.  If anyone has any objections, please let us know.

Obviously it's a bit late now, but...

> ------------------
> 
> From: Avi Kivity <avi@redhat.com>
> 
> commit 9581d442b9058d3699b4be568b6e5eae38a41493 upstream
>
> kvm reloads the host's fs and gs blindly, however the underlying segment
> descriptors may be invalid due to the user modifying the ldt after loading
> them.
> 
> Fix by using the safe accessors (loadsegment() and load_gs_index()) instead
> of home grown unsafe versions.
> 
> This is CVE-2010-3698.
> 
> Signed-off-by: Avi Kivity <avi@redhat.com>
> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
[...]

Avi, you surely knew this commit was buggy (specifically for i386
userland on an amd64 kernel) since you also committed:

commit c8770e7ba63bb5dd8fe5f9d251275a8fa717fb78
Author: Avi Kivity <avi@redhat.com>
Date:   Thu Nov 11 12:37:26 2010 +0200

    KVM: VMX: Fix host userspace gsbase corruption

I realise it wasn't ready for stable as Linus only pulled it in
2.6.37-rc3, but surely that means this neither of the changes should
have gone into 2.6.32.26.  Why didn't you respond to the review??

Ben.

-- 
Ben Hutchings
Once a job is fouled up, anything done to improve it makes it worse.

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Re: [Stable-review] [22/45] KVM: Fix fs/gs reload oops with invalid ldt

[Avi Kivity]

On 11/26/2010 03:15 AM, Ben Hutchings wrote:
> Greg KH<gregkh@suse.de>  wrote:
> >  2.6.32-stable review patch.  If anyone has any objections, please let us know.
>
> Obviously it's a bit late now, but...
>
> >  ------------------
> >
> >  From: Avi Kivity<avi@redhat.com>
> >
> >  commit 9581d442b9058d3699b4be568b6e5eae38a41493 upstream
> >
> >  kvm reloads the host's fs and gs blindly, however the underlying segment
> >  descriptors may be invalid due to the user modifying the ldt after loading
> >  them.
> >
> >  Fix by using the safe accessors (loadsegment() and load_gs_index()) instead
> >  of home grown unsafe versions.
> >
> >  This is CVE-2010-3698.
> >
> >  Signed-off-by: Avi Kivity<avi@redhat.com>
> >  Signed-off-by: Marcelo Tosatti<mtosatti@redhat.com>
> >  Signed-off-by: Greg Kroah-Hartman<gregkh@suse.de>
> [...]
>
> Avi, you surely knew this commit was buggy (specifically for i386
> userland on an amd64 kernel) since you also committed:
>
> commit c8770e7ba63bb5dd8fe5f9d251275a8fa717fb78
> Author: Avi Kivity<avi@redhat.com>
> Date:   Thu Nov 11 12:37:26 2010 +0200
>
>      KVM: VMX: Fix host userspace gsbase corruption
>
> I realise it wasn't ready for stable as Linus only pulled it in
> 2.6.37-rc3, but surely that means this neither of the changes should
> have gone into 2.6.32.26.  Why didn't you respond to the review??
>

I don't actually read those review emails, there are too many of them.

The fix will go into 2.6.32.stable in time.  Fixing the vulnerability 
was more important than i386-on-x86_64 anyway.

-- 
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.

Re: [Stable-review] [22/45] KVM: Fix fs/gs reload oops with invalid ldt

[Greg KH]

On Fri, Nov 26, 2010 at 10:32:05AM +0200, Avi Kivity wrote:
> On 11/26/2010 03:15 AM, Ben Hutchings wrote:
>> Greg KH<gregkh@suse.de>  wrote:
>> >  2.6.32-stable review patch.  If anyone has any objections, please let us know.
>>
>> Obviously it's a bit late now, but...
>>
>> >  ------------------
>> >
>> >  From: Avi Kivity<avi@redhat.com>
>> >
>> >  commit 9581d442b9058d3699b4be568b6e5eae38a41493 upstream
>> >
>> >  kvm reloads the host's fs and gs blindly, however the underlying segment
>> >  descriptors may be invalid due to the user modifying the ldt after loading
>> >  them.
>> >
>> >  Fix by using the safe accessors (loadsegment() and load_gs_index()) instead
>> >  of home grown unsafe versions.
>> >
>> >  This is CVE-2010-3698.
>> >
>> >  Signed-off-by: Avi Kivity<avi@redhat.com>
>> >  Signed-off-by: Marcelo Tosatti<mtosatti@redhat.com>
>> >  Signed-off-by: Greg Kroah-Hartman<gregkh@suse.de>
>> [...]
>>
>> Avi, you surely knew this commit was buggy (specifically for i386
>> userland on an amd64 kernel) since you also committed:
>>
>> commit c8770e7ba63bb5dd8fe5f9d251275a8fa717fb78
>> Author: Avi Kivity<avi@redhat.com>
>> Date:   Thu Nov 11 12:37:26 2010 +0200
>>
>>      KVM: VMX: Fix host userspace gsbase corruption
>>
>> I realise it wasn't ready for stable as Linus only pulled it in
>> 2.6.37-rc3, but surely that means this neither of the changes should
>> have gone into 2.6.32.26.  Why didn't you respond to the review??
>>
>
> I don't actually read those review emails, there are too many of them.

Please read the ones that are cc:ed to you, otherwise it's pretty
pointless for me to send them out :(

thanks,

greg k-h