Note: This bug is displayed in read-only format because
the product is no longer active in Red Hat Bugzilla.
RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.
When the "compat" method is specified in the nsswitch.conf file, special entries containing the "+" or "-" characters are allowed to be used in the /etc/passwd file. Previously, when the finger utility was run with a "username" argument on a host that had the special entries in /etc/passwd, finger terminated with a segmentation fault. With this update, the code that handles the "username" argument has been fixed to perform the necessary checks and the finger utility no longer crashes in the described scenario.
DescriptionLars Kellogg-Stedman
2012-04-25 19:49:36 UTC
Description of problem:
We have a NIS-bound system with 'passwd: compat' in /etc/nsswitch.conf. The final line in /etc/passwd on this was system was:
+:
On this system, "finger" would segfault when passed a username as an
argument. On line 188 in finger/util.c, finger was calling strncpy()
like this:
int
match(struct passwd *pw, const char *user)
{
char *p;
int i, j, ct, rv=0;
char *rname;
strncpy(tbuf, pw->pw_gecos, TBUFLEN);
With our /etc/passwd file configured as described, pw->pw_gecos would
have a NULL rather than empty value, causing strncpy() to segfault.
An ideal fix would be to have match() return 0 if pw->pw_gecos is
NULL, as in this patch:
diff --git a/finger/util.c b/finger/util.c
index 8e28d63..c82bc86 100644
--- a/finger/util.c
+++ b/finger/util.c
@@ -186,6 +186,9 @@ match(struct passwd *pw, const char *user)
int i, j, ct, rv=0;
char *rname;
+ if (pw->pw_gecos == NULL)
+ return 0;
+
strncpy(tbuf, pw->pw_gecos, TBUFLEN);
tbuf[TBUFLEN-1] = 0; /* guarantee null termination */
p = tbuf;
Comment 3Lars Kellogg-Stedman
2012-10-11 13:02:30 UTC
Problem identified and patch provided...any updates on this issue? Thanks!
(In reply to Lars Kellogg-Stedman from comment #3)
> Problem identified and patch provided...any updates on this issue? Thanks!
Hi Lars.
If everything goes well, this issue will be fixed in the next RHEL-6 minor
update release.
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.
http://rhn.redhat.com/errata/RHBA-2014-0587.html
Description of problem: We have a NIS-bound system with 'passwd: compat' in /etc/nsswitch.conf. The final line in /etc/passwd on this was system was: +: On this system, "finger" would segfault when passed a username as an argument. On line 188 in finger/util.c, finger was calling strncpy() like this: int match(struct passwd *pw, const char *user) { char *p; int i, j, ct, rv=0; char *rname; strncpy(tbuf, pw->pw_gecos, TBUFLEN); With our /etc/passwd file configured as described, pw->pw_gecos would have a NULL rather than empty value, causing strncpy() to segfault. An ideal fix would be to have match() return 0 if pw->pw_gecos is NULL, as in this patch: diff --git a/finger/util.c b/finger/util.c index 8e28d63..c82bc86 100644 --- a/finger/util.c +++ b/finger/util.c @@ -186,6 +186,9 @@ match(struct passwd *pw, const char *user) int i, j, ct, rv=0; char *rname; + if (pw->pw_gecos == NULL) + return 0; + strncpy(tbuf, pw->pw_gecos, TBUFLEN); tbuf[TBUFLEN-1] = 0; /* guarantee null termination */ p = tbuf;