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Bug 2208240 - systemd can send non-UTF8 messages over DBus, causing DBus to disconnect it
Summary: systemd can send non-UTF8 messages over DBus, causing DBus to disconnect it
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 9
Classification: Red Hat
Component: systemd
Version: 9.2
Hardware: All
OS: Linux
unspecified
medium
Target Milestone: rc
: ---
Assignee: Michal Sekletar
QA Contact: Frantisek Sumsal
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2023-05-18 10:57 UTC by Michal Sekletar
Modified: 2023-11-07 11:31 UTC (History)
3 users (show)

Fixed In Version: systemd-252-16.el9
Doc Type: If docs needed, set a value
Doc Text:
Clone Of:
Environment:
Last Closed: 2023-11-07 08:54:03 UTC
Type: Bug
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Github redhat-plumbers systemd-rhel9 pull 167 0 None open (#2208240) core/mount: escape invalid UTF8 char in dbus reply 2023-05-18 15:00:41 UTC
Red Hat Issue Tracker RHELPLAN-157587 0 None None None 2023-05-18 10:58:41 UTC
Red Hat Product Errata RHBA-2023:6640 0 None None None 2023-11-07 08:54:24 UTC

Description Michal Sekletar 2023-05-18 10:57:33 UTC 
This bug was initially created as a copy of Bug #2158724

I am copying this bug because: 



Description of problem:

This is a continuation of BZ #2158167 (related to PID recycling) and the condition making the latter be hit from time to time.

We have a customer seeing the scopes started for crond and sshd not getting destroyed inside systemd-logind when last PID exits.
This causes systemd-logind to "leak" sessions (state files remaining in /run/systemd/sessions in CLOSING state) and eventually systemd-logind to hit BZ #2158167 when PID recycling happens.
With the fix for BZ #2158167, the customer sees "Maximum number of sessions reached (8192)" after 1 day or so.

I requested an strace of systemd and systemd-logind to try to understand the condition where this would happen.
It appears the issue is due to having an issue within systemd which cannot abandon the scope:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
Scope session-50854.scope is not running, cannot abandon.
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

Due to this, systemd-logind never deletes its internal data related to the session.

I don't know how to reproduce the condition for now. Comparing customer's strace and my strace, I see a lot of differences in DBus messages being issued by systemd to systemd-logind:

Customer:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
1     18:36:02.172067 sendmsg(19<UNIX:[397683477->397687257]>, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="l\4\1\1H\0\0\0\24\35\3\0q\0\0\0\1\1o\0\31\0\0\0/org/freedesktop/systemd1\0\0\0\0\0\0\0\2\1s\0 \0\0\0org.freedesktop.systemd1.Manager\0\0\0\0\0\0\0\0\3\1s\0\6\0\0\0JobNew\0\0\10\1g\0\3uos"..., iov_len=136}, {iov_base="\347.]\0%\0\0\0/org/freedesktop/systemd1/job/6106855\0\0\0\23\0\0\0session-50854.scope\0", iov_len=72}], msg_iovlen=2, msg_controllen=0, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL) = 208 <0.000013>
1     18:36:02.179388 sendmsg(19<UNIX:[397683477->397687257]>, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="l\4\1\1Q\0\0\0\26\35\3\0z\0\0\0\1\1o\0\31\0\0\0/org/freedesktop/systemd1\0\0\0\0\0\0\0\2\1s\0 \0\0\0org.freedesktop.systemd1.Manager\0\0\0\0\0\0\0\0\3\1s\0\n\0\0\0JobRemoved\0\0\0\0\0\0"..., iov_len=144}, {iov_base="\347.]\0%\0\0\0/org/freedesktop/systemd1/job/6106855\0\0\0\23\0\0\0session-50854.scope\0\4\0\0\0done\0", iov_len=81}], msg_iovlen=2, msg_controllen=0, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL) = 225 <0.000018>
1     18:36:02.623647 sendmsg(19<UNIX:[397683477->397687257]>, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="l\4\1\0015\0\0\0N\35\3\0o\0\0\0\1\1o\0\37\0\0\0/org/freedesktop/systemd1/agent\0\2\1s\0\36\0\0\0org.freedesktop.systemd1.Agent\0\0\3\1s\0\10\0\0\0Released\0\0\0\0\0\0\0\0\10\1g\0\1s\0\0", iov_len=128}, {iov_base="0\0\0\0/user.slice/user-11469.slice/session-50854.scope\0", iov_len=53}], msg_iovlen=2, msg_controllen=0, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL) = 181 <0.000029>
1     18:36:02.628222 sendmsg(19<UNIX:[397683477->397687257]>, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="l\3\1\1>\0\0\0P\35\3\0_\0\0\0\5\1u\0\263i\0\0\6\1s\0\n\0\0\0:1.7022504\0\0\0\0\0\0\4\1s\0(\0\0\0org.freedesktop.systemd1.ScopeNotRunning\0\0\0\0\0\0\0\0\10\1g\0\1s\0\0", iov_len=112}, {iov_base="9\0\0\0Scope session-50854.scope is not running, cannot abandon.\0", iov_len=62}], msg_iovlen=2, msg_controllen=0, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL) = 174 <0.000017>
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

Mine:
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
1     11:09:19.108569 sendmsg(51<UNIX:[17880->24141]>, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="l\4\1\1K\0\0\0\365\0\0\0p\0\0\0\1\1o\0\31\0\0\0/org/freedesktop/systemd1\0\0\0\0\0\0\0\2\1s\0 \0\0\0org.freedesktop.systemd1.Manager\0\0\0\0\0\0\0\0\3\1s\0\7\0\0\0UnitNew\0\10\1g\0\2so\0", iov_len=128}, {iov_base="\17\0\0\0session-3.scope\0002\0\0\0/org/freedesktop/systemd1/unit/session_2d3_2escope\0", iov_len=75}], msg_iovlen=2, msg_controllen=0, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL <unfinished ...>
1     11:09:19.108642 sendmsg(51<UNIX:[17880->24141]>, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="l\4\1\1@\0\0\0\366\0\0\0q\0\0\0\1\1o\0\31\0\0\0/org/freedesktop/systemd1\0\0\0\0\0\0\0\2\1s\0 \0\0\0org.freedesktop.systemd1.Manager\0\0\0\0\0\0\0\0\3\1s\0\6\0\0\0JobNew\0\0\10\1g\0\3uos"..., iov_len=136}, {iov_base="\240\2\0\0!\0\0\0/org/freedesktop/systemd1/job/672\0\0\0\17\0\0\0session-3.scope\0", iov_len=64}], msg_iovlen=2, msg_controllen=0, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL <unfinished ...>
1     11:09:19.113703 sendmsg(51<UNIX:[17880->24141]>, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="l\4\1\1I\0\0\0\367\0\0\0z\0\0\0\1\1o\0\31\0\0\0/org/freedesktop/systemd1\0\0\0\0\0\0\0\2\1s\0 \0\0\0org.freedesktop.systemd1.Manager\0\0\0\0\0\0\0\0\3\1s\0\n\0\0\0JobRemoved\0\0\0\0\0\0"..., iov_len=144}, {iov_base="\240\2\0\0!\0\0\0/org/freedesktop/systemd1/job/672\0\0\0\17\0\0\0session-3.scope\0\4\0\0\0done\0", iov_len=73}], msg_iovlen=2, msg_controllen=0, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL) = 217 <0.000008>
1     11:09:19.225074 sendmsg(51<UNIX:[17880->24141]>, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="l\4\1\1K\0\0\0\2\1\0\0x\0\0\0\1\1o\0\31\0\0\0/org/freedesktop/systemd1\0\0\0\0\0\0\0\2\1s\0 \0\0\0org.freedesktop.systemd1.Manager\0\0\0\0\0\0\0\0\3\1s\0\v\0\0\0UnitRemoved\0\0\0\0\0"..., iov_len=136}, {iov_base="\17\0\0\0session-3.scope\0002\0\0\0/org/freedesktop/systemd1/unit/session_2d3_2escope\0", iov_len=75}], msg_iovlen=2, msg_controllen=0, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL) = 211 <0.000013>
1     11:09:19.226435 sendmsg(51<UNIX:[17880->24141]>, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="l\4\1\1-\0\0\0\3\1\0\0o\0\0\0\1\1o\0\37\0\0\0/org/freedesktop/systemd1/agent\0\2\1s\0\36\0\0\0org.freedesktop.systemd1.Agent\0\0\3\1s\0\10\0\0\0Released\0\0\0\0\0\0\0\0\10\1g\0\1s\0\0", iov_len=128}, {iov_base="(\0\0\0/user.slice/user-0.slice/session-3.scope\0", iov_len=45}], msg_iovlen=2, msg_controllen=0, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL) = 173 <0.000019>
1     11:09:19.226783 sendmsg(51<UNIX:[17880->24141]>, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="l\4\1\1K\0\0\0\5\1\0\0p\0\0\0\1\1o\0\31\0\0\0/org/freedesktop/systemd1\0\0\0\0\0\0\0\2\1s\0 \0\0\0org.freedesktop.systemd1.Manager\0\0\0\0\0\0\0\0\3\1s\0\7\0\0\0UnitNew\0\10\1g\0\2so\0", iov_len=128}, {iov_base="\17\0\0\0session-3.scope\0002\0\0\0/org/freedesktop/systemd1/unit/session_2d3_2escope\0", iov_len=75}], msg_iovlen=2, msg_controllen=0, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL) = 203 <0.000015>
1     11:09:19.226857 sendmsg(51<UNIX:[17880->24141]>, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="l\4\1\1K\0\0\0\6\1\0\0x\0\0\0\1\1o\0\31\0\0\0/org/freedesktop/systemd1\0\0\0\0\0\0\0\2\1s\0 \0\0\0org.freedesktop.systemd1.Manager\0\0\0\0\0\0\0\0\3\1s\0\v\0\0\0UnitRemoved\0\0\0\0\0"..., iov_len=136}, {iov_base="\17\0\0\0session-3.scope\0002\0\0\0/org/freedesktop/systemd1/unit/session_2d3_2escope\0", iov_len=75}], msg_iovlen=2, msg_controllen=0, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL <unfinished ...>
1     11:09:19.227418 sendmsg(51<UNIX:[17880->24141]>, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="l\4\1\1K\0\0\0\10\1\0\0p\0\0\0\1\1o\0\31\0\0\0/org/freedesktop/systemd1\0\0\0\0\0\0\0\2\1s\0 \0\0\0org.freedesktop.systemd1.Manager\0\0\0\0\0\0\0\0\3\1s\0\7\0\0\0UnitNew\0\10\1g\0\2so\0", iov_len=128}, {iov_base="\17\0\0\0session-3.scope\0002\0\0\0/org/freedesktop/systemd1/unit/session_2d3_2escope\0", iov_len=75}], msg_iovlen=2, msg_controllen=0, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL <unfinished ...>
1     11:09:19.227492 sendmsg(51<UNIX:[17880->24141]>, {msg_name=NULL, msg_namelen=0, msg_iov=[{iov_base="l\4\1\1K\0\0\0\t\1\0\0x\0\0\0\1\1o\0\31\0\0\0/org/freedesktop/systemd1\0\0\0\0\0\0\0\2\1s\0 \0\0\0org.freedesktop.systemd1.Manager\0\0\0\0\0\0\0\0\3\1s\0\v\0\0\0UnitRemoved\0\0\0\0\0"..., iov_len=136}, {iov_base="\17\0\0\0session-3.scope\0002\0\0\0/org/freedesktop/systemd1/unit/session_2d3_2escope\0", iov_len=75}], msg_iovlen=2, msg_controllen=0, msg_flags=0}, MSG_DONTWAIT|MSG_NOSIGNAL <unfinished ...>
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

MAJOR DIFFERENCE: I don't see any UnitNew/UnitRemoved messages on customer's system


Version-Release number of selected component (if applicable):

systemd-239.68.el8
Suspected to be also seen on older systemd (we had a case with another customer in the past, before issue disappeared completely)

How reproducible:

Often/Always on customer system, cannot reproduce locally
Comment 6 errata-xmlrpc 2023-11-07 08:54:03 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory (systemd bug fix and enhancement update), and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://access.redhat.com/errata/RHBA-2023:6640
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