Bug 73346

Summary: pam_wheel segmentation faults when getlogin() fails
Product: [Retired] Red Hat Linux Reporter: Göran Uddeborg <goeran>
Component: pamAssignee: Jindrich Novy <jnovy>
Status: CLOSED CURRENTRELEASE QA Contact: Jay Turner <jturner>
Severity: medium Docs Contact:
Priority: medium    
Version: 8.0CC: kjell, pknirsch, srevivo
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Hardware: i386   
OS: Linux   
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Fixed In Version: Doc Type: Bug Fix
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Last Closed: 2004-09-21 08:36:12 UTC Type: ---
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Description Flags
Patch to avoid this segmentation violation. none

Description Göran Uddeborg 2002-09-03 10:08:34 UTC 
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Description of problem:
If pam_wheel is used without the use_uid argument, and if it is used in an
environment where getlogin() fails (and thus returns null), the process gets an
segmentation fault.

Version-Release number of selected component (if applicable): 0.75-40


How reproducible:
Always

Steps to Reproduce:
1.Enter a line like this in /etc/pam.d/su.  (Note, no use_uid!)
auth       required     /lib/security/pam_wheel.so
2.Run "xterm -ut"
3.In this xterm, do "su" from one ordinary user to another.
	

Actual Results:  Segmentation violation

Expected Results:  I guess pam_wheel should deny access in this case, but it
should do so in an orderly way.

Additional info:

The reason is that the return value from getlogin() is used directly in a call
to _pam_getpwnam_r() without checking it first.  Afterwards the returned value
is checked, but that is too late.  The attached patch suggests a trivial solution.
Comment 1 Göran Uddeborg 2002-09-03 10:09:35 UTC 
Created attachment 74644 [details]
Patch to avoid this segmentation violation.