Bug 449358 - nscd breaks getservbyport()
nscd breaks getservbyport()
Product: Fedora
Classification: Fedora
Component: glibc (Show other bugs)
i386 Linux
low Severity high
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Assigned To: Jakub Jelinek
Fedora Extras Quality Assurance
Depends On:
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Reported: 2008-06-02 07:57 EDT by Roman Kagan
Modified: 2008-07-23 03:08 EDT (History)
0 users

See Also:
Fixed In Version: 2.8-8
Doc Type: Bug Fix
Doc Text:
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Clone Of:
Last Closed: 2008-07-23 03:08:31 EDT
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RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: ---

Attachments (Terms of Use)
potential fix (untested) (663 bytes, patch)
2008-06-02 08:59 EDT, Roman Kagan
no flags Details | Diff

  None (edit)
Description Roman Kagan 2008-06-02 07:57:10 EDT
Description of problem:
When nscd is running, getservbyport() returns garbage.

With stock /etc/services, it returns spr-itunes (0 port) for any query.  With 0
port removed from /etc/services, it returns NULL for any query.

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

How reproducible:

Steps to Reproduce:

Use the following program:

#include <netdb.h>
#include <stdio.h>

int main(int argc, char **argv)
	struct servent *s;
	s = getservbyport(htons(atoi(argv[1])), argv[2]);
	if (s)
		printf("%s\n", s->s_name);
		printf("port not found\n");

Without nscd everything is fine:

# service nscd stop
Stopping nscd:                                             [  OK  ]
# ./bug 25 tcp
# ./bug 7425 tcp
port not found

With nscd and 0 port in /etc/services (stock /etc/services from setup package):

# awk '$2 == "0/tcp" {print}' /etc/services
spr-itunes	0/tcp			# Shirt Pocket netTunes
spl-itunes	0/tcp			# Shirt Pocket launchTunes
# service nscd stop
Stopping nscd:                                             [FAILED]
# rm -f /var/db/nscd/*
# service nscd start
Starting nscd:                                             [  OK  ]
# ./bug 25 tcp
# ./bug 7425 tcp

With nscd and without 0 port in /etc/services:

# awk '$2 != "0/tcp"' /etc/services > /etc/services.nozero
# cat /etc/services.nozero > /etc/services
# service nscd stop
Stopping nscd:                                             [FAILED]
# rm -f /var/db/nscd/*
# service nscd start
Starting nscd:                                             [  OK  ]
# ./bug 25 tcp
port not found
# ./bug 7425 tcp
port not found
Comment 1 Roman Kagan 2008-06-02 08:59:14 EDT
Created attachment 307357 [details]
potential fix (untested)

Seems like the problem is in __nscd_getservbyport_r(), where the port is
converted to a string at the end of the buffer, but then the beginning of the
buffer is passed down to nscd_getserv_r().
Comment 2 Jakub Jelinek 2008-06-03 06:51:07 EDT
Thanks, looks correct, applied to CVS.
Comment 3 Jakub Jelinek 2008-06-15 18:42:21 EDT
Fixed in rawhide glibc and will be eventually backported.
Comment 4 Fedora Update System 2008-07-08 16:27:23 EDT
glibc-2.8-7 has been submitted as an update for Fedora 9
Comment 5 Fedora Update System 2008-07-23 03:08:21 EDT
glibc-2.8-8 has been pushed to the Fedora 9 stable repository.  If problems still persist, please make note of it in this bug report.

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