Bug 167917 - pam_krb5 sets PAM_AUTHTOK with rubbish instead of PAM_OLDAUTHTOK with a valid pointer in pam_sm_chauthtok
pam_krb5 sets PAM_AUTHTOK with rubbish instead of PAM_OLDAUTHTOK with a valid...
Product: Red Hat Enterprise Linux 4
Classification: Red Hat
Component: pam_krb5 (Show other bugs)
All Linux
medium Severity high
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Assigned To: Nalin Dahyabhai
Brian Brock
Depends On:
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Reported: 2005-09-09 11:16 EDT by John Haxby
Modified: 2010-02-12 13:49 EST (History)
0 users

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Fixed In Version:
Doc Type: Bug Fix
Doc Text:
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Last Closed: 2010-02-12 13:49:30 EST
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Attachments (Terms of Use)
Proposed patch. (735 bytes, patch)
2005-09-09 11:35 EDT, John Haxby
no flags Details | Diff

  None (edit)
Description John Haxby 2005-09-09 11:16:11 EDT
From Bugzilla Helper:
User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-GB; rv:1.7.10) Gecko/20050719 Red Hat/1.0.6-1.4.1 Firefox/1.0.6

Description of problem:
During the PAM_PRELIM_CHECK phase of pam_sm_chauthtok, a call to pam_set_item() set the PAM_AUTHTOK item to the validated password.   It correctly *uses* PAM_OLDAUTHTOK for use_first_pass is true and correctly sets PAM_AUTHTOK to the *new* password in the PAM_UPDATE_AUTHTOK phase.

As you can imagine, this causes problems for stacked modules that follow pam_krb5 that want to use_first_pass.

Rather worse than that both calls to pam_set_item() pass "&password" as the last parameter.  Since this last parameter is passed to strdup() you store rubbish in pamh->authtok (if you're lucky) or experience a painful segmentation fault (if you're not).   That's why I've set this to "high" -- it's a matter of luck that passwd(1) doesn't crash.

The other calls to pam_set_item() in auth.c are, thankfully, correct.

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

How reproducible:

Steps to Reproduce:
1. grep -n pam_set_item .../pam_krb5-2.1.2-1/src/password.c

Actual Results:  187: pam_set_item(pamh, PAM_AUTHTOK, &password);
250: pam_set_item(pamh, PAM_AUTHTOK, &password);

Expected Results:  187: pam_set_item(pamh, PAM_OLDAUTHTOK, password);
250: pam_set_item(pamh, PAM_AUTHTOK, password);

Additional info:
Comment 1 John Haxby 2005-09-09 11:35:23 EDT
Created attachment 118639 [details]
Proposed patch.

Just to save you some work :-)	 I've tested this, pam_krb5 now behaves as
expected when changing passwords.
Comment 2 Nalin Dahyabhai 2010-02-12 13:49:30 EST
Fixed in 2.1.16.  Thanks!

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