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[RESEND,0/2] Don't use SIGMINSTKSZ when enforcing alternative signal stack size for compat tasks

Message ID 1536158083-30166-1-git-send-email-will.deacon@arm.com
Headers show
Series Don't use SIGMINSTKSZ when enforcing alternative signal stack size for compat tasks | expand

Message

Will Deacon Sept. 5, 2018, 2:34 p.m. UTC
Hi all,

This is a resend of:

  http://lists.infradead.org/pipermail/linux-arm-kernel/2018-July/593559.html

now based on 4.19-rc2.

The Debian folks have observed a failure in the 32-bit arm glibc testsuite
when running under a 64-bit kernel. They tracked this down to sigaltstack(2)
enforcing the alternative signal stack to be at least SIGMINSTKSZ bytes,
which is higher for native arm64 tasks than compat 32-bit tasks.

These patches resolve the issue by allowing an architecture to define
COMPAT_SIGMINSTKSZ for compat tasks, which is then used by the sigaltstack
checking code.

Feedback welcome,

Will

--->8

Will Deacon (2):
  signal: Introduce COMPAT_SIGMINSTKSZ for use in compat_sys_sigaltstack
  arm64: compat: Provide definition for COMPAT_SIGMINSTKSZ

 arch/arm64/include/asm/compat.h |  1 +
 include/linux/compat.h          |  3 +++
 kernel/signal.c                 | 14 +++++++++-----
 3 files changed, 13 insertions(+), 5 deletions(-)

-- 
2.1.4

Comments

Will Deacon Sept. 12, 2018, 1:11 p.m. UTC | #1
Hi all,

[+ more people from get_maintainers.pl]

On Wed, Sep 05, 2018 at 03:34:41PM +0100, Will Deacon wrote:
> This is a resend of:

> 

>   http://lists.infradead.org/pipermail/linux-arm-kernel/2018-July/593559.html

> 

> now based on 4.19-rc2.

> 

> The Debian folks have observed a failure in the 32-bit arm glibc testsuite

> when running under a 64-bit kernel. They tracked this down to sigaltstack(2)

> enforcing the alternative signal stack to be at least SIGMINSTKSZ bytes,

> which is higher for native arm64 tasks than compat 32-bit tasks.

> 

> These patches resolve the issue by allowing an architecture to define

> COMPAT_SIGMINSTKSZ for compat tasks, which is then used by the sigaltstack

> checking code.

> 

> Feedback welcome,


Any comments on this, please? I'd really like to get this fixed, since
Debian have an outstanding issue without these patches merged. I'm happy
to take them via arm64, but would really like an Ack on the changes to
signal.c first...

Thanks,

Will

> Will Deacon (2):

>   signal: Introduce COMPAT_SIGMINSTKSZ for use in compat_sys_sigaltstack

>   arm64: compat: Provide definition for COMPAT_SIGMINSTKSZ

> 

>  arch/arm64/include/asm/compat.h |  1 +

>  include/linux/compat.h          |  3 +++

>  kernel/signal.c                 | 14 +++++++++-----

>  3 files changed, 13 insertions(+), 5 deletions(-)

> 

> -- 

> 2.1.4

>
Steve McIntyre Sept. 26, 2018, 10:36 a.m. UTC | #2
On Wed, Sep 05, 2018 at 03:34:41PM +0100, Will Deacon wrote:
>Hi all,

>

>This is a resend of:

>

>  http://lists.infradead.org/pipermail/linux-arm-kernel/2018-July/593559.html

>

>now based on 4.19-rc2.

>

>The Debian folks have observed a failure in the 32-bit arm glibc testsuite

>when running under a 64-bit kernel. They tracked this down to sigaltstack(2)

>enforcing the alternative signal stack to be at least SIGMINSTKSZ bytes,

>which is higher for native arm64 tasks than compat 32-bit tasks.

>

>These patches resolve the issue by allowing an architecture to define

>COMPAT_SIGMINSTKSZ for compat tasks, which is then used by the sigaltstack

>checking code.

>

>Feedback welcome,


Apologies for the delayed response here - conference travel etc . got
in the way... I've just tested and I can confirm that this patchset
fixes our reported bug (as in https://bugs.debian.org/904385). Thanks
Will!

Tested-by: Steve McIntyre <93sam@debian.org>


--
Steve McIntyre
steve.mcintyre@arm.com

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Steve McIntyre Sept. 28, 2018, 1:18 p.m. UTC | #3
[ Re-sending without the corporate footer garbage... ]

On Wed, Sep 05, 2018 at 03:34:41PM +0100, Will Deacon wrote:
>Hi all,

>

>This is a resend of:

>

>  http://lists.infradead.org/pipermail/linux-arm-kernel/2018-July/593559.html

>

>now based on 4.19-rc2.

>

>The Debian folks have observed a failure in the 32-bit arm glibc testsuite

>when running under a 64-bit kernel. They tracked this down to sigaltstack(2)

>enforcing the alternative signal stack to be at least SIGMINSTKSZ bytes,

>which is higher for native arm64 tasks than compat 32-bit tasks.

>

>These patches resolve the issue by allowing an architecture to define

>COMPAT_SIGMINSTKSZ for compat tasks, which is then used by the sigaltstack

>checking code.

>

>Feedback welcome,


Apologies for the delayed response here - conference travel etc . got
in the way... I've just tested and I can confirm that this patchset
fixes our reported bug (as in https://bugs.debian.org/904385). Thanks
Will!

Tested-by: Steve McIntyre <93sam@debian.org>


-- 
Steve McIntyre  <93sam@debian.org>
Catalin Marinas Oct. 1, 2018, 10:43 a.m. UTC | #4
On Fri, Sep 28, 2018 at 02:18:11PM +0100, Steve McIntyre wrote:
> On Wed, Sep 05, 2018 at 03:34:41PM +0100, Will Deacon wrote:

> >Hi all,

> >

> >This is a resend of:

> >

> >  http://lists.infradead.org/pipermail/linux-arm-kernel/2018-July/593559.html

> >

> >now based on 4.19-rc2.

> >

> >The Debian folks have observed a failure in the 32-bit arm glibc testsuite

> >when running under a 64-bit kernel. They tracked this down to sigaltstack(2)

> >enforcing the alternative signal stack to be at least SIGMINSTKSZ bytes,

> >which is higher for native arm64 tasks than compat 32-bit tasks.

> >

> >These patches resolve the issue by allowing an architecture to define

> >COMPAT_SIGMINSTKSZ for compat tasks, which is then used by the sigaltstack

> >checking code.

> >

> >Feedback welcome,

> 

> Apologies for the delayed response here - conference travel etc . got

> in the way... I've just tested and I can confirm that this patchset

> fixes our reported bug (as in https://bugs.debian.org/904385). Thanks

> Will!

> 

> Tested-by: Steve McIntyre <93sam@debian.org>


Thanks for confirming Steve.

As there is no functional change for other architectures, I'll queue
both patches through the arm64 tree. If anyone objects, please let me
know before the merging window.

-- 
Catalin