Public bug reported:
/home/mcmanus/t/t>lsb_release -rd
Description: Ubuntu 8.04.1
Release: 8.04
/home/mcmanus/t/t>apt-cache policy libc6
libc6:
Installed: 2.7-10ubuntu3
Candidate: 2.7-10ubuntu3
Version table:
*** 2.7-10ubuntu3 0
500 http://us.archive.ubuntu.com hardy/main Packages
100 /var/lib/dpkg/status
--
I think this is an upstream bug.
This sample program crashes due to a stack overflow on a thread spawned by
glibc. I am not sure if that is also true on 32bit.
(Complile as gcc poc.c -lresolv -ldl -lpthread -lanl )
#define _GNU_SOURCE
#include <netdb.h>
#include <string.h>
main()
{
struct gaicb gb, *list[1];
struct addrinfo hints;
memset (&hints, 0 , sizeof (hints));
list[0] = &gb;
memset (&gb, 0, sizeof (gb));
gb.ar_name = "www.ducksong.com";
gb.ar_service = NULL;
gb.ar_request = &hints;
gb.ar_result = NULL;
getaddrinfo_a (GAI_WAIT, list, 1, NULL);
return 0;
}
In addition to the SEGV, valgrind reports
==21077==
==21077== Process terminating with default action of signal 11 (SIGSEGV)
==21077== Bad permissions for mapped region at address 0x4023A88
==21077== at 0x57477CC: __res_vinit (res_init.c:571)
==21077== by 0x7FF0005FF: ???
==21077== by 0x802BF: ???
The following patch to libc lets the program run without error and gets
valgrind a clean bill of health.
diff -ur glibc-2.7/nptl/sysdeps/pthread/gai_misc.h
../../glibc-2.7/nptl/sysdeps/pthread/gai_misc.h
--- glibc-2.7/nptl/sysdeps/pthread/gai_misc.h 2007-07-28 15:30:21.000000000
-0400
+++ ../../glibc-2.7/nptl/sysdeps/pthread/gai_misc.h 2008-09-09
11:02:59.293997492 -0400
@@ -97,7 +97,7 @@
pthread_attr_setdetachstate (&attr, PTHREAD_CREATE_DETACHED);
/* The helper thread needs only very little resources. */
- (void) pthread_attr_setstacksize (&attr, PTHREAD_STACK_MIN);
+ (void) pthread_attr_setstacksize (&attr, 24*1024);
/* Block all signals in the helper thread. To do this thoroughly we
temporarily have to block all signals here. */
** Affects: glibc (Ubuntu)
Importance: Undecided
Status: New
--
getaddrinfo_a stack overflow on 64bit - hardy
https://bugs.launchpad.net/bugs/268195
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