Bug 916469 – sys-apps/systemd-254.5: udev segfaults on hppa with >=linux-6.3 when using MemoryDenyWriteExecute

• Product: Gentoo Linux
• Status: RESOLVED FIXED

[Description Sam James 2023-10-29 08:10:01 UTC]

I was optimistic that bug 916468 was the cause of this but it turns out that was just a sandbox issue.

All I know so far is when I upgraded from 253.6 -> 254.5, I got a bunch of segfaults in systemd-udev and couldn't boot.

Just filing this so I can dump stuff as I dig into it.

[Comment 1 Sam James 2023-10-29 08:17:47 UTC]

OK, I can reproduce it within an nspawn when I upgrade it..


Oct 29 08:17:30 ladder systemd-nspawn[12550]:          Starting systemd-network-generator.service...
Oct 29 08:17:30 ladder systemd-nspawn[12550]:          Starting systemd-remount-fs.service...
Oct 29 08:17:30 ladder systemd-nspawn[12550]:          Starting systemd-tmpfiles-setup-dev-early.service...
Oct 29 08:17:30 ladder systemd-nspawn[12550]: [  OK  ] Mounted dev-hugepages.mount.
Oct 29 08:17:30 ladder systemd-nspawn[12550]: systemd-journald.service: Main process exited, code=killed, status=11/SEGV
Oct 29 08:17:30 ladder systemd-nspawn[12550]: systemd-journald.service: Failed with result 'signal'.
Oct 29 08:17:30 ladder systemd-nspawn[12550]: [FAILED] Failed to start systemd-journald.service.
Oct 29 08:17:30 ladder systemd-nspawn[12550]: See 'systemctl status systemd-journald.service' for detail

[Comment 2 Sam James 2023-10-29 09:36:50 UTC]

Oct 29 09:36:12 ladder (md-udevd)[25741]: systemd-udevd.service: Enabled MemoryDenyWriteExecute= with PR_SET_MDWE
Oct 29 09:36:12 ladder (md-udevd)[25741]: systemd-udevd.service: Executing: /usr/lib/systemd/systemd-udevd
Oct 29 09:36:12 ladder systemd[1]: systemd-journald.service: Received EPOLLHUP on stored fd 45 (stored), closing.
Oct 29 09:36:12 ladder systemd[1]: Received SIGCHLD from PID 25741 (systemd-udevd).
Oct 29 09:36:12 ladder systemd[1]: Child 25741 (systemd-udevd) died (code=killed, status=11/SEGV)
Oct 29 09:36:12 ladder systemd[1]: systemd-udevd.service: Child 25741 belongs to systemd-udevd.service.
Oct 29 09:36:12 ladder systemd[1]: systemd-udevd.service: Main process exited, code=killed, status=11/SEGV
░░ Subject: Unit process exited

hppa doesn't support MemoryDenyWriteExecute because it requires executable stacks still.

[Comment 3 Sam James 2023-10-29 09:43:30 UTC]

The new function added in https://github.com/systemd/systemd/pull/25276 doesn't reflect the exclusion of HPPA in https://github.com/systemd/systemd/commit/344e6b62fceea0f5fac1f1efcff7e0ccf4a4e3c8#diff-60141857536525beb87708eaf458438b24ce034aed48172f0db7ee1cd1acc648R1723 for seccomp.

[Comment 4 Sam James 2023-10-31 04:35:38 UTC]

Reported to kernel people as well at https://lore.kernel.org/linux-parisc/[e-mail]/T/#u.

[Comment 5 Larry the Git Cow 2023-10-31 06:05:54 UTC]

The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=ae7e31e30db7921510ce4a0830bc6627f878b5d1

commit ae7e31e30db7921510ce4a0830bc6627f878b5d1
Author:     Sam James <[e-mail]>
AuthorDate: 2023-10-31 06:04:18 +0000
Commit:     Sam James <[e-mail]>
CommitDate: 2023-10-31 06:04:18 +0000

    profiles/arch/hppa: mask >=sys-apps/systemd-254
    
    Fails to boot.
    
    Bug: https://bugs.gentoo.org/916469
    Signed-off-by: Sam James <[e-mail]>

 profiles/arch/hppa/package.mask | 5 +++++
 1 file changed, 5 insertions(+)

[Comment 6 Larry the Git Cow 2023-12-24 12:03:48 UTC]

The bug has been referenced in the following commit(s):

https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=b241cb5a399a820201412b5c6905c4e029da7f4e

commit b241cb5a399a820201412b5c6905c4e029da7f4e
Author:     Sam James <[e-mail]>
AuthorDate: 2023-12-24 12:03:27 +0000
Commit:     Sam James <[e-mail]>
CommitDate: 2023-12-24 12:03:39 +0000

    profiles/arch/hppa: drop stale systemd mask
    
    This was fixed in the kernel.
    
    Bug: https://bugs.gentoo.org/916469
    Bug: https://bugs.gentoo.org/919107
    Signed-off-by: Sam James <[e-mail]>

 profiles/arch/hppa/package.mask | 5 -----
 1 file changed, 5 deletions(-)

[Comment 7 Sam James 2023-12-24 14:22:43 UTC]

commit 3ed9692ef1ca5c763b74fd5bb1dbb6f6b2cfb6bc
Author: Mike Pagano <[e-mail]>
Date:   Mon Nov 20 07:11:47 2023 -0500

    sys-kernel/gentoo-sources: add 6.6.2 and two risc patches

    Added:
    prctl: Temporarily disable prctl(PR_SET_MDWE) on parisc
    parisc: Fix mmap_base calculation when stack grows upwards

    Signed-off-by: Mike Pagano <[e-mail]>

[...]

commit 28674786cd9912643c04021d5b3605eedf846057
Author: Mike Pagano <[e-mail]>
Date:   Tue Nov 28 14:17:17 2023 -0500

    sys-kernel/gentoo-sources: add 6.6.3, removed redundant patch

    Removed:
    1720_parisc-gen-mmap-top-down-layout-and-brk-randomization.patch

    Signed-off-by: Mike Pagano <[e-mail]>