[krbdev.mit.edu #6534] getaddrinfo in src/util/support/fake-addrinfo.c causes leak

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>Submitter-Id:	net
>Originator:	Rainer Weikusat
>Organization:
	MadPartners LTD
>Confidential:	no
>Synopsis:	getaddrinfo in src/util/support/fake-addrinfo.c causes leak
>Severity:	non-critical
>Priority:	medium
>Category:	krb5-libs
>Class:		sw-bug
>Release:	1.7
>Environment:
	
System: Linux fever 2.6.30 #2 SMP Thu Jun 18 19:35:55 CEST 2009 i686 GNU/Linux


>Description:
	The function whose name was given in the synopsis contains a workaround
	for a history problem with the glibc getaddrinfo:

		Linux libc version 6 (libc-2.2.4.so on Debian) is broken.
		
		[...]

 		The glibc 2.2.5 sources indicate that the canonical name is
		*not* allocated separately, it's just some extra storage tacked
		on the end of the addrinfo structure.  So, let's try this
		approach: If getaddrinfo sets ai_canonname, we'll replace the
		*first* one with allocated storage,

	This issue was fixed by Ulrich Drepper on 2004/08/17, cf

		http://sourceware.org/git/?p=glibc.git;a=commit;f=ChangeLog;h=b93437642453ab93f7da79a15ca29cc66048e828

	which implies that the ai_canonname-member has been allocated via strdup 
	at least since glibc release 2.3.4. The workaround mentionedc above overwrites
	this allocated name with a newly allocated one, causing a memory leak.
>How-To-Repeat:
	use krb5_sname_to_princiapal
>Fix:
	A somewhat crude way to fix this issues is provided by the patch below
	(the warning is there because I didn't find the patchlevel anywhere in
	the glibc includes, but need this for 2.3.6)

diff -pru krb5-1.7.orig/src/util/support/fake-addrinfo.c krb5-1.7/src/util/support/fake-addrinfo.c
--- krb5-1.7.orig/src/util/support/fake-addrinfo.c      2008-12-01 18:09:59.000000000 +0100
+++ krb5-1.7/src/util/support/fake-addrinfo.c   2009-07-21 19:19:16.000000000 +0200
@@ -140,7 +140,13 @@ extern /*@dependent@*/ char *gai_strerro
 #endif
 
 #if defined (__linux__) && defined(HAVE_GETADDRINFO)
+#ifdef __GLIBC_MINOR__
+#if __GLIBC_MINOR__ < 3
 # define COPY_FIRST_CANONNAME
+#elif __GLIBC_MINOR__ == 3
+#warning GLIBC 2.3 < 2.3.4 needs COPY_FIRST_CANONNAME
+#endif
+#endif
 #endif
 
 #ifdef _AIX