Re: FAILED: patch "[PATCH] signal: Don't always set SA_IMMUTABLE for forced signals" failed to apply to 5.15-stable tree

[Thomas Backlund <tmb@iki.fi>]

Den 2021-11-23 kl. 21:24, skrev ebiederm@xmission.com:
> Greg KH <gregkh@linuxfoundation.org> writes:
>
>> On Tue, Nov 23, 2021 at 07:29:43PM +0200, Thomas Backlund wrote:
>>> Den 2021-11-22 kl. 14:31, skrev gregkh@linuxfoundation.org:
>>>> The patch below does not apply to the 5.15-stable tree.
>>>> If someone wants it applied there, or to any other stable or longterm
>>>> tree, then please email the backport, including the original git commit
>>>> id to <stable@vger.kernel.org>.
>>>>
>>>> thanks,
>>>>
>>>> greg k-h
>>>
>>> It will apply if you add this one first:
>>>
>>>  From 26d5badbccddcc063dc5174a2baffd13a23322aa Mon Sep 17 00:00:00 2001
>>> From: "Eric W. Biederman" <ebiederm@xmission.com>
>>> Date: Wed, 20 Oct 2021 12:43:59 -0500
>>> Subject: [PATCH] signal: Implement force_fatal_sig
>>>
>>>
>>>
>>>
>>> and if the other patch for signal that has similar description should land
>>> in 5.15:
>>>
>>>  From fcb116bc43c8c37c052530ead79872f8b2615711 Mon Sep 17 00:00:00 2001
>>> From: "Eric W. Biederman" <ebiederm@xmission.com>
>>> Date: Thu, 18 Nov 2021 14:23:21 -0600
>>> Subject: [PATCH] signal: Replace force_fatal_sig with force_exit_sig when in
>>> doubt
>>>
>>>
>>>
>>> then the list is looks something like:
>>>
>>>
>>>  From 941edc5bf174b67f94db19817cbeab0a93e0c32a Mon Sep 17 00:00:00 2001
>>> From: "Eric W. Biederman" <ebiederm@xmission.com>
>>> Date: Wed, 20 Oct 2021 12:44:00 -0500
>>> Subject: [PATCH] exit/syscall_user_dispatch: Send ordinary signals on
>>> failure
>>>
>>>  From 83a1f27ad773b1d8f0460d3a676114c7651918cc Mon Sep 17 00:00:00 2001
>>> From: "Eric W. Biederman" <ebiederm@xmission.com>
>>> Date: Wed, 20 Oct 2021 12:43:53 -0500
>>> Subject: [PATCH] signal/powerpc: On swapcontext failure force SIGSEGV
>>>
>>>  From 9bc508cf0791c8e5a37696de1a046d746fcbd9d8 Mon Sep 17 00:00:00 2001
>>> From: "Eric W. Biederman" <ebiederm@xmission.com>
>>> Date: Wed, 20 Oct 2021 12:43:57 -0500
>>> Subject: [PATCH] signal/s390: Use force_sigsegv in default_trap_handler
>>>
>>>  From c317d306d55079525c9610267fdaf3a8a6d2f08b Mon Sep 17 00:00:00 2001
>>> From: "Eric W. Biederman" <ebiederm@xmission.com>
>>> Date: Wed, 20 Oct 2021 12:44:01 -0500
>>> Subject: [PATCH] signal/sparc32: Exit with a fatal signal when
>>>   try_to_clear_window_buffer fails
>>>
>>>  From 086ec444f86660e103de8945d0dcae9b67132ac9 Mon Sep 17 00:00:00 2001
>>> From: "Eric W. Biederman" <ebiederm@xmission.com>
>>> Date: Wed, 20 Oct 2021 12:44:02 -0500
>>> Subject: [PATCH] signal/sparc32: In setup_rt_frame and setup_fram use
>>>   force_fatal_sig
>>>
>>>  From 1fbd60df8a852d9c55de8cd3621899cf4c72a5b7 Mon Sep 17 00:00:00 2001
>>> From: "Eric W. Biederman" <ebiederm@xmission.com>
>>> Date: Wed, 20 Oct 2021 12:43:56 -0500
>>> Subject: [PATCH] signal/vm86_32: Properly send SIGSEGV when the vm86 state
>>> cannot be saved.
>>>
>>>  From 695dd0d634df8903e5ead8aa08d326f63b23368a Mon Sep 17 00:00:00 2001
>>> From: "Eric W. Biederman" <ebiederm@xmission.com>
>>> Date: Wed, 20 Oct 2021 12:44:03 -0500
>>> Subject: [PATCH] signal/x86: In emulate_vsyscall force a signal instead of
>>> calling do_exit
>>>
>>>  From 26d5badbccddcc063dc5174a2baffd13a23322aa Mon Sep 17 00:00:00 2001
>>> From: "Eric W. Biederman" <ebiederm@xmission.com>
>>> Date: Wed, 20 Oct 2021 12:43:59 -0500
>>> Subject: [PATCH] signal: Implement force_fatal_sig
>>>
>>>  From e21294a7aaae32c5d7154b187113a04db5852e37 Mon Sep 17 00:00:00 2001
>>> From: "Eric W. Biederman" <ebiederm@xmission.com>
>>> Date: Mon, 25 Oct 2021 10:50:57 -0500
>>> Subject: [PATCH] signal: Replace force_sigsegv(SIGSEGV) with
>>>   force_fatal_sig(SIGSEGV)
>>>
>>>  From e349d945fac76bddc78ae1cb92a0145b427a87ce Mon Sep 17 00:00:00 2001
>>> From: "Eric W. Biederman" <ebiederm@xmission.com>
>>> Date: Thu, 18 Nov 2021 11:11:13 -0600
>>> Subject: [PATCH] signal: Don't always set SA_IMMUTABLE for forced signals
>>>
>>>  From fcb116bc43c8c37c052530ead79872f8b2615711 Mon Sep 17 00:00:00 2001
>>> From: "Eric W. Biederman" <ebiederm@xmission.com>
>>> Date: Thu, 18 Nov 2021 14:23:21 -0600
>>> Subject: [PATCH] signal: Replace force_fatal_sig with force_exit_sig when in
>>> doubt
>>>
>>>
>>>
>>> Applying them in listed order on top of 5.14.4 and builds/runs on i586,
>>> x86_64, armv7hl, aarch64
>> That series list is crazy, let me go try it and see what blows up! :)
> Maybe I am wrong but I think "Don't always set SA_IMMUTABLE for forced
> signals" will apply if you drop the hunk modifying force_fatal_sig.
> Then you don't need to backport all of the cleanups just the fix.
>
> I will take a quick look and verify that.


that's why i wrote: "if the other patch for signal that has similar 
description should land"

(meaning "signal: Replace force_fatal_sig with force_exit_sig when in 
doubt")

as thats the one needing the whole patch series...


since going by patch descriptions for:

"signal: Don't always set SA_IMMUTABLE for forced signals"

"signal: Replace force_fatal_sig with force_exit_sig when in doubt"


both has the info:

"Unfortunately this broke debuggers[1][2] which reasonably expect
to be able to trap synchronous SIGTRAP and SIGSEGV even when
the target process is not configured to handle those signals."

and the second even has:
"This avoids userspace regressions as older kernels exited with do_exit
which debuggers also can not intercept."


or is the patch description on the second patch somewhat misleading ?

--
Thomas