Bug 428439 - sshd segfaults during kerberos auth with krb4 credentials
sshd segfaults during kerberos auth with krb4 credentials
Product: Red Hat Enterprise Linux 4
Classification: Red Hat
Component: pam_krb5 (Show other bugs)
All Linux
medium Severity medium
: rc
: ---
Assigned To: Nalin Dahyabhai
Brian Brock
Depends On:
  Show dependency treegraph
Reported: 2008-01-11 10:38 EST by Adam Stokes
Modified: 2010-10-22 17:41 EDT (History)
1 user (show)

See Also:
Fixed In Version: RHBA-2008-0712
Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of:
Last Closed: 2008-07-24 15:55:05 EDT
Type: ---
Regression: ---
Mount Type: ---
Documentation: ---
Verified Versions:
Category: ---
oVirt Team: ---
RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)
pass v4_get_creds correct ctx (384 bytes, patch)
2008-01-11 10:38 EST, Adam Stokes
no flags Details | Diff

  None (edit)
Description Adam Stokes 2008-01-11 10:38:43 EST
Description of problem:
Customer is always getting a segmentation fault whenever trying to authenticate
on  a sshd server with pam_krb5 configured to convert Krb5 credentials to Krb4.
This was a new feature added on request of this very customer with BZ#201265.

An uninitialized variable could be passed down the stack, after a quick chat
with the package maintainer (nalin) I have written the attached patch
"pam_krb5-2.1.17-1.navid_uninit_ctx.diff" which appears to solve the issue for
the customer.

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

How reproducible:

Steps to Reproduce:
1. on the ssh server, edited /etc/krb5.conf and added:

pam = {
 krb4_convert = true
 external = sshd

2. on the ssh client, edited /etc/ssh/ssh_config and added:


3. Update pam system-auth to do the krb4 conversion
Actual results:
Connection is closed since sshd dies after successful authentication:
ssh(1562) debug1: Authentications that can continue:
ssh(1562) debug1: Next authentication method: gssapi-with-mic
ssh(1562) debug1: Delegating credentials
ssh(1562) debug1: Delegating credentials
ssh(1562) debug1: Authentication succeeded (gssapi-with-mic).
ssh(1562) debug1: channel 0: new [client-session]
ssh(1562) debug1: Entering interactive session.
ssh(1562) debug1: channel 0: free: client-session, nchannels 1
Connection to refrh4es-i386 closed by remote host.
Connection to refrh4es-i386 closed.
ssh(1562) debug1: Transferred: stdin 0, stdout 0, stderr 89 bytes in 0.2 seconds

debug3: mm_share_sync: Share sync
debug3: mm_share_sync: Share sync end
debug1: temporarily_use_uid: 0/0 (e=0/0)
debug1: restore_uid: 0/0
debug1: PAM: establishing credentials
debug3: PAM: opening session
Segmentation fault (core dumped)

Expected results:
sshd stays alive and authentication succeeds or sshd fails gracefully

Additional info:
Comment 1 Adam Stokes 2008-01-11 10:38:44 EST
Created attachment 291399 [details]
pass v4_get_creds correct ctx
Comment 2 RHEL Product and Program Management 2008-01-11 10:45:42 EST
This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux maintenance release.  Product Management has requested
further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed
products.  This request is not yet committed for inclusion in an Update
Comment 8 errata-xmlrpc 2008-07-24 15:55:05 EDT
An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.


Note You need to log in before you can comment on or make changes to this bug.