Consultation on backport 97e3d26b5e5f("x86/mm: Randomize per-cpu entry area") to stable
Hi peter:
Do you have any plans to backport this patch[1] to the stable branch of the lower version, such as 4.19.y ?
When I try to backport this patch to 5.10.y, I met some KASAN[2] and KASLR[3] related issues. Although they were finally solved, there were still some detours in the process.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=97e3d26b5e5f371b3ee223d94dd123e6c442ba80
[2] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3f148f3318140035e87decc1214795ff0755757b
[3]
Best Regards,
Tong
.
My fault, the third patch link is missing:)
Best Regards,
Tong
.
Quoted 15 lines · Tong Tiangen
Hi peter:
Do you have any plans to backport this patch[1] to the stable branch of the lower version, such as 4.19.y ?
When I try to backport this patch to 5.10.y, I met some KASAN[2] and KASLR[3] related issues. Although they were finally solved, there were still some detours in the process.[3]
Best Regards,
Tong.
Greg KH
maintainerQuoted 4 lines · Tong Tiangen
Hi peter:
Do you have any plans to backport this patch[1] to the stable branch of the lower version, such as 4.19.y ?
Why? That is a new feature for 6.2 why would it be needed to fix anything in really old kernels?
Quoted 3 lines
When I try to backport this patch to 5.10.y, I met some KASAN[2] and KASLR[3] related issues. Although they were finally solved, there were still some detours in the process.
Send your series of backports to the list for review please if they match the stable kernel rules.
But why can't you just use the 6.2 kernel instead of something obsolete like 4.19?
thanks,
greg k-h
Quoted 8 lines · Greg KH
Quoted 4 lines · Tong Tiangen
Hi peter:
Do you have any plans to backport this patch[1] to the stable branch of the lower version, such as 4.19.y ?
Why? That is a new feature for 6.2 why would it be needed to fix anything in really old kernels?
Hi Greg:
This patch fix CVE-2023-0597[1], this CVE report a flaw possibility of memory leak. And this is important for some products using this stable version.
[1] https://bugzilla.redhat.com/show_bug.cgi?id=2165926
Quoted 7 lines
Quoted 4 lines
When I try to backport this patch to 5.10.y, I met some KASAN[2] and KASLR[3] related issues. Although they were finally solved, there were still some detours in the process.
Send your series of backports to the list for review please if they match the stable kernel rules.
OK.
Quoted 8 lines
But why can't you just use the 6.2 kernel instead of something obsolete like 4.19?
thanks,
greg k-h
.
Thanks.
Tong
.
Greg KH
maintainerQuoted 9 lines · Tong Tiangen
Quoted 6 lines · Greg KH
Quoted 4 lines · Tong Tiangen
Hi peter:
Do you have any plans to backport this patch[1] to the stable branch of the lower version, such as 4.19.y ?
Quoted 6 lines
Quoted 2 lines
Why? That is a new feature for 6.2 why would it be needed to fix anything in really old kernels?
Hi Greg:
This patch fix CVE-2023-0597[1],
The kernel developers do not care about CVEs as they are almost always invalid and do not mean anything, sorry. It is well known that companies like Red Hat use them to make up for broken internal engineering policies.
Are you sure this really is a valid problem that must be fixed in older kernels?
Quoted 2 lines
this CVE report a flaw possibility of memory leak. And this is important for some products using this stable version.
What exact memory leak are you referring to?
thanks,
greg k-h
Quoted 13 lines · Greg KH
Quoted 12 lines · Tong Tiangen
Quoted 8 lines · Greg KH
Quoted 4 lines · Tong Tiangen
Hi peter:
Do you have any plans to backport this patch[1] to the stable branch of the lower version, such as 4.19.y ?
Why? That is a new feature for 6.2 why would it be needed to fix anything in really old kernels?
Quoted 6 lines
Quoted 3 lines
Hi Greg:
This patch fix CVE-2023-0597[1],
The kernel developers do not care about CVEs as they are almost always invalid and do not mean anything,
Ok, thanks.
Quoted 1 line
sorry. It is well known that, companies like Red Hat use them to make up for broken internal engineering policies.
Yeah, For company's internal engineering policies, the CVE with certain impact must be repaired.
Quoted 8 lines
Are you sure this really is a valid problem that must be fixed in older kernels?
Quoted 2 lines
this CVE report a flaw possibility of memory leak. And this is important for some products using this stable version.
What exact memory leak are you referring to?
Sorry for Inaccurate description, the memory leak means: a potential security risk of kernel memory information disclosure caused by no randomization of the exception stacks.
Quoted 5 lines
thanks,
greg k-h
.
Thanks,
Tong
.
Greg KH
maintainerQuoted 23 lines · Tong Tiangen
Quoted 13 lines · Greg KH
Quoted 12 lines · Tong Tiangen
Quoted 8 lines · Greg KH
Quoted 4 lines · Tong Tiangen
Hi peter:
Do you have any plans to backport this patch[1] to the stable branch of the lower version, such as 4.19.y ?
Why? That is a new feature for 6.2 why would it be needed to fix anything in really old kernels?
Quoted 6 lines
Quoted 3 lines
Hi Greg:
This patch fix CVE-2023-0597[1],
The kernel developers do not care about CVEs as they are almost always invalid and do not mean anything,
Quoted 8 lines
Ok, thanks.
Quoted 2 lines
sorry. It is well known that, companies like Red Hat use them to make up for broken internal engineering policies.
Yeah, For company's internal engineering policies, the CVE with certain impact must be repaired.
So you are letting an opaque US government agency, and random third party companies, dictate your company's internal engineering policies and resource allocations? That feels very very odd and ripe for abuse.
Also note that MITRE refuses to allocate CVEs for many real kernel issues for unknown reasons, (i.e. they reject all of my requests), so you are getting only a small subset of real issues here.
Also, how do you handle revocation of CVEs that are obviously invalid and/or don't actually do anything (like this one?)
Quoted 11 lines
Quoted 7 lines
Are you sure this really is a valid problem that must be fixed in older kernels?
Quoted 2 lines
this CVE report a flaw possibility of memory leak. And this is important for some products using this stable version.
What exact memory leak are you referring to?
Sorry for Inaccurate description, the memory leak means: a potential security risk of kernel memory information disclosure caused by no randomization of the exception stacks.
And are you sure this can really happen? Have you proven this?
And why is this really an issue, KASR is a known-week-defense and almost useless against local attacks.
Anyway, please provide working patches if you think this really is an issue.
And please revisit your company's policies, they do not seem very sane :)
thanks,
greg k-h
Quoted 58 lines · Greg KH
Quoted 23 lines · Tong Tiangen
Quoted 13 lines · Greg KH
Quoted 12 lines · Tong Tiangen
Quoted 8 lines · Greg KH
Quoted 4 lines · Tong Tiangen
Hi peter:
Do you have any plans to backport this patch[1] to the stable branch of the lower version, such as 4.19.y ?
Why? That is a new feature for 6.2 why would it be needed to fix anything in really old kernels?
Quoted 6 lines
Quoted 3 lines
Hi Greg:
This patch fix CVE-2023-0597[1],
The kernel developers do not care about CVEs as they are almost always invalid and do not mean anything,
Quoted 8 lines
Ok, thanks.
Quoted 2 lines
sorry. It is well known that, companies like Red Hat use them to make up for broken internal engineering policies.
Yeah, For company's internal engineering policies, the CVE with certain impact must be repaired.
So you are letting an opaque US government agency, and random third party companies, dictate your company's internal engineering policies and resource allocations? That feels very very odd and ripe for abuse.
Also note that MITRE refuses to allocate CVEs for many real kernel issues for unknown reasons, (i.e. they reject all of my requests), so you are getting only a small subset of real issues here.
Also, how do you handle revocation of CVEs that are obviously invalid and/or don't actually do anything (like this one?)
Quoted 11 lines
Quoted 7 lines
Are you sure this really is a valid problem that must be fixed in older kernels?
Quoted 2 lines
this CVE report a flaw possibility of memory leak. And this is important for some products using this stable version.
What exact memory leak are you referring to?
Sorry for Inaccurate description, the memory leak means: a potential security risk of kernel memory information disclosure caused by no randomization of the exception stacks.
And are you sure this can really happen? Have you proven this?
Quoted 7 lines
And why is this really an issue, KASR is a known-week-defense and almost useless against local attacks.
Anyway, please provide working patches if you think this really is an issue.
And please revisit your company's policies, they do not seem very sane :)
Hi Greg:
Thanks for these very useful suggestions and we will revisit our policies :)
Thanks,
Tong
.
Quoted 5 lines
thanks,
greg k-h
.
A message that is not in the archive (sent off-list or not yet received): CALxfFW6zgTEj3b==g5tWXaufAaVCAe6Uh8pKda-O20OOToRAJg@mail.gmail.com
Quoted 5 lines · Seth Jenkins
Quoted 3 lines
So you are letting an opaque US government agency, and random third party companies, dictate your company's internal engineering policies and resource allocations? That feels very very odd and ripe for abuse.
I wholeheartedly agree with gregkh that the CVE system is flawed in numerous ways and generates many false positives, however in this case, this issue is a real issue with real security impact that received a real patch upstream. The idea of backporting this to earlier kernels probably warrants discussion if someone is willing to bite off that work. But this gets into the fuzzy "backporting exploit mitigations to stable" conversation.
Quoted 8 lines
Quoted 1 line
And are you sure this can really happen? Have you proven this?
Yes this can really, provably, happen:
https://googleprojectzero.blogspot.com/2022/12/exploiting-CVE-2022-42703-bringing-back-the-stack-attack.html <https://googleprojectzero.blogspot.com/2022/12/exploiting-CVE-2022-42703-bringing-back-the-stack-attack.html>Quoted 1 line
And why is this really an issue, KAS[L]R is a known-weak-defense and
almost
Quoted 1 line
useless against local attacks.
Granted, Peter Z's fix does help to mitigate the impact from remote attackers but yes this fix does not resolve the security impact from local exploits.
Thank you seth.
Yes, for this specific CVE issue, KASLR is indeed a mitigation measure.
Quoted 96 lines · On Tue, Feb 21, 2023 at 7:30 AM Tong Tiangen <[email protected]…
在 2023/2/21 18:40, Greg KH 写道:
> On Tue, Feb 21, 2023 at 05:19:42PM +0800, Tong Tiangen wrote:
>>
>>
>> 在 2023/2/21 16:40, Greg KH 写道:
>>> On Tue, Feb 21, 2023 at 03:46:27PM +0800, Tong Tiangen wrote:
>>>>
>>>>
>>>> 在 2023/2/21 15:30, Greg KH 写道:
>>>>> On Tue, Feb 21, 2023 at 03:19:05PM +0800, Tong Tiangen wrote:
>>>>>> Hi peter:
>>>>>>
>>>>>> Do you have any plans to backport this patch[1] to the
stable branch of the
>>>>>> lower version, such as 4.19.y ?
>>>>>
>>>>> Why? That is a new feature for 6.2 why would it be needed to fix
>>>>> anything in really old kernels?
>>>>
>>>> Hi Greg:
>>>>
>>>> This patch fix CVE-2023-0597[1],
>>>
>>> The kernel developers do not care about CVEs as they are almost
always
>>> invalid and do not mean anything,
>>
>> Ok, thanks.
>>
>>
>>> sorry. It is well known that, companies like Red Hat use them
to make
>>> up for broken internal engineering policies.
>>
>> Yeah, For company's internal engineering policies, the CVE with
certain
>> impact must be repaired.
>
> So you are letting an opaque US government agency, and random third
> party companies, dictate your company's internal engineering policies
> and resource allocations? That feels very very odd and ripe for
abuse.
>
> Also note that MITRE refuses to allocate CVEs for many real kernel
> issues for unknown reasons, (i.e. they reject all of my requests), so
> you are getting only a small subset of real issues here.
>
> Also, how do you handle revocation of CVEs that are obviously invalid
> and/or don't actually do anything (like this one?)
>
>>> Are you sure this really is a valid problem that must be fixed
in older
>>> kernels?
>>>
>>>> this CVE report a flaw possibility of memory leak. And this is
>>>> important for some products using this stable version.
>>>
>>> What exact memory leak are you referring to?
>>
>> Sorry for Inaccurate description, the memory leak means: a potential
>> security risk of kernel memory information disclosure caused by no
>> randomization of the exception stacks.
>
> And are you sure this can really happen? Have you proven this?
>
> And why is this really an issue, KASR is a known-week-defense and
almost
> useless against local attacks.
>
> Anyway, please provide working patches if you think this really is an
> issue.
>
> And please revisit your company's policies, they do not seem very
sane :)
Hi Greg:
Thanks for these very useful suggestions and we will revisit our
policies :)
Thanks,
Tong
.
>
> thanks,
>
> greg k-h
> .