Bug 1678510

Summary:	sddm-helper creates weird directories inside my home directory at each login
Product:	[Fedora] Fedora	Reporter:	Andrew Zabolotny <anpaza>
Component:	sddm	Assignee:	Martin Bříza <m>
Status:	CLOSED ERRATA	QA Contact:	Fedora Extras Quality Assurance <extras-qa>
Severity:	medium	Docs Contact:
Priority:	unspecified
Version:	29	CC:	jgrulich, kde-sig, me, m, pierluigi.fiorini, rdieter, sdatskevich, vladsol2009
Target Milestone:	---
Target Release:	---
Hardware:	x86_64
OS:	Linux
Whiteboard:
Fixed In Version:	sddm-0.18.0-4.fc29	Doc Type:	If docs needed, set a value
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2019-04-15 17:43:37 UTC	Type:	Bug
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Andrew Zabolotny 2019-02-19 00:09:25 UTC

Description of problem:
After each login I get a new subdirectory created inside my home directory.
I mean such things:
drwx------.  3 alice alice  4096 фев 19 02:51 'p�'$'\021''�U'/

Inside there's an empty .cache directory and inside .cache there's an empty .xsession-errors.

Version-Release number of selected component (if applicable):
sddm-0.18.0-1.fc29.x86_64

How reproducible:
Always

Steps to Reproduce:
1. Network install Fedora 29 with KDE desktop from USB stick
2. Create a user account
3. Login and look inside ~

Actual results:
There's a just-created directory with random chars in its name.

Additional info:
I enabled audit and tracked the bug down to sddm-helper creating these directories:

type=PROCTITLE msg=audit(19.02.2019 02:51:02.381:251) : proctitle=/usr/libexec/sddm-helper --socket /tmp/sddm-autheeb5bb4c-d6a5-4448-89be-ca0c1883c1e8 --id 1 --start /usr/bin/startkde --user alitype=PATH msg=audit(19.02.2019 02:51:02.381:251) : item=1 name=/home/alice/p�\021�U inode=11272248 dev=fd:03 mode=dir,700 ouid=alice ogid=alice rdev=00:00 obj=system_u:object_r:user_home_t:s0 nametype=CREATE cap_fp=none cap_fi=none cap_fe=0 cap_fver=0
type=PATH msg=audit(19.02.2019 02:51:02.381:251) : item=0 name=/home/alice/ inode=112
72193 dev=fd:03 mode=dir,700 ouid=alice ogid=alice rdev=00:00 obj=unconfined_u:object_r:user_home_dir_t:s0 nametype=PARENT cap_fp=none cap_fi=none cap_fe=0 cap_fver=0
type=CWD msg=audit(19.02.2019 02:51:02.381:251) : cwd=/home/alice
type=SYSCALL msg=audit(19.02.2019 02:51:02.381:251) : arch=x86_64 syscall=mkdir success=yes exit=0 a0=0x55da11a466b8 a1=0777 a2=0x15 a3=0x0 items=2 ppid=1727 pid=1752 auid=alice uid=alice gid=alice euid=alice suid=alice fsuid=alice egid=alice sgid=alice fsgid=alice tty=(none) ses=4 comm=sddm-helper exe=/usr/libexec/sddm-helper subj=system_u:system_r:xdm_t:s0-s0:c0.c1023 key=(null)

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There's a very similar bug #1665740 but they blame abrt there. I have erased abrt and his countless minions off the face of my OS and I still get those directories created at (almost) every login. So abrt is not the cause.

Comment 1 Vladislav Solovei 2019-03-01 10:29:20 UTC

Fedora 29 x86_64, updated.
I have the same problem.


type=AVC msg=audit(1551435502.201:259): avc:  denied  { write } for  pid=1800 comm="sddm-helper" path="/home/username/3V/.cache/xsession-errors" dev="dm-1" ino=202884691 scontext=system_u:system_r:xdm_t:s0-s0:c0.c1023 tcontext=system_u:object_r:user_home_t:s0 tclass=file permissive=0

- in this case sddm-helper tries to create *V folder. The first symbol is always different.
On example:
�U
PV
3V

Comment 2 Andrew Zabolotny 2019-03-09 08:23:45 UTC

Looks like the weird name is somehow related to a) login name and b) locale.
As far as I understand both me and Vladislav are using Cyrillic locales.

Comment 3 Vladislav Solovei 2019-03-09 14:26:44 UTC

No, that's not a locale issue.
I'm using en_US.UTF-8.

Occasionally, sddm_helper gets a corrupted passwd structure from getpwnam_r() in function UserSession::setupChildProcess()
Why? I don't know.
Regardless of username, locale, etc...
Different CPUs?

Comment 4 Vladislav Solovei 2019-03-09 16:59:33 UTC

So, i guess, the reason ins line 233 in src/helper/UserSession.cpp:
free(buffer)

C code to demonstrate this behavior https://pastebin.com/fpWyg78c
My output:
before: /home/zend
after: J

Comment 5 Fedora Update System 2019-03-15 20:18:46 UTC

sddm-0.18.0-4.fc29 has been submitted as an update to Fedora 29. https://bodhi.fedoraproject.org/updates/FEDORA-2019-96c964d319

Comment 6 Fedora Update System 2019-04-15 17:43:37 UTC

sddm-0.18.0-4.fc29 has been pushed to the Fedora 29 stable repository. If problems still persist, please make note of it in this bug report.