Red Hat Bugzilla – Bug 971515
[abrt] xscreensaver-base-5.21-7.fc19: Process /usr/bin/xscreensaver was killed by signal 11 (SIGSEGV)
Last modified: 2015-02-17 10:28:52 EST
Version-Release number of selected component:
cmdline: xscreensaver -no-splash
runlevel: N 5
Thread no. 1 (10 frames)
#2 spt_init at setproctitle.c:152
#3 call_init at dl-init.c:82
#4 _dl_init at dl-init.c:131
#5 dl_open_worker at dl-open.c:566
#6 _dl_catch_error at dl-error.c:177
#7 _dl_open at dl-open.c:656
#8 dlopen_doit at dlopen.c:66
#9 _dl_catch_error at dl-error.c:177
#10 _dlerror_run at dlerror.c:163
#11 __dlopen at dlopen.c:87
Created attachment 757759 [details]
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Created attachment 757761 [details]
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Created attachment 757770 [details]
Looks like pam library is calling dlopen() and segv happens there.
Once switching to glibc.
The segv is in libbsd, not in glibc:
#2 spt_init (argc=2, argv=0x7fff22d1fb98, envp=0x0) at setproctitle.c:152
base = 0x7fff22d2099c "xscreensaver"
end = 0x7fff22d209a9 "-no-splash"
nul = 0x7fff22d209a8 ""
tmp = <optimized out>
i = 0
Is the environment expected to be NULL? If it is, then it's a bug in libbsd, or else it would be nice to have a reproducer that replicates this behaviour.
(In reply to Siddhesh Poyarekar from comment #12)
> Is the environment expected to be NULL?
At least clearenv() seems to set environ to NULL (I don't know if pam authentification calls clearenv()). Terry, would you attach /etc/pam.d/xscreensaver and /etc/pam.d/system-auth ?
# Fedora Core 5:
auth include system-auth
# SuSE 9.0: (along with "configure --with-passwd-helper" and "unix2_chkpwd")
# auth required pam_unix2.so nullok
# Distant past:
# auth required /lib/security/pam_pwdb.so shadow nullok
# Account validation
account include system-auth
[OLYMPIC\tpolzin@linuxadmin pam.d]$ cat system-auth
# This file is auto-generated.
# User changes will be destroyed the next time authconfig is run.
auth required pam_env.so
auth sufficient pam_unix.so nullok try_first_pass
auth requisite pam_succeed_if.so uid >= 1000 quiet_success
auth sufficient pam_winbind.so use_first_pass
auth required pam_deny.so
account required pam_access.so
account required pam_unix.so broken_shadow
account sufficient pam_localuser.so
account sufficient pam_succeed_if.so uid < 1000 quiet
account [default=bad success=ok user_unknown=ignore] pam_winbind.so
account required pam_permit.so
password requisite pam_pwquality.so try_first_pass retry=3 type=
password sufficient pam_unix.so sha512 shadow nullok try_first_pass use_authtok
password sufficient pam_winbind.so use_authtok
password required pam_deny.so
session optional pam_keyinit.so revoke
session required pam_limits.so
-session optional pam_systemd.so
session optional pam_mkhomedir.so
session [success=1 default=ignore] pam_succeed_if.so service in crond quiet use_uid
session required pam_unix.so
session optional pam_winbind.so
ls -l system-auth
lrwxrwxrwx. 1 root root 14 Mar 8 11:49 system-auth -> system-auth-ac
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The first problem is that setproctitle_init must never be called from dlopen, it was moved (in possibly later versions I think) into a static stub that has to be linked against he application instead. The reason being that you can't manipulate the environ in an MT-safe fashion once the application has started, so you link against a stub that runs setproctitle_init as an application constructor.
Secondly, the envp should not be null. If the application manipulated envp to be null, then it breaks the expectations of setproctitle_init, and should be fixed and is probably related to the late initialization of libbsd.
Assigning back to xscreensaver for analysis.
Fedora 19 changed to end-of-life (EOL) status on 2015-01-06. Fedora 19 is
no longer maintained, which means that it will not receive any further
security or bug fix updates. As a result we are closing this bug.
If you can reproduce this bug against a currently maintained version of
Fedora please feel free to reopen this bug against that version. If you
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