From: Karel Zak <kzak@redhat.com>
Date: Mon, 21 May 2012 07:58:42 +0000 (+0200)
Subject: login: fix segmentation fault in log_utmp
X-Git-Tag: v2.21.2~16
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=a508da14a670bbb52f5a9778ceffcdcf827af483;p=thirdparty%2Futil-linux.git

login: fix segmentation fault in log_utmp

 ctx->tty_number is optional...

Addresses: https://bugzilla.redhat.com/show_bug.cgi?id=822705
Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/login-utils/login.c b/login-utils/login.c
index a984af62e4..826c2eb8f0 100644
--- a/login-utils/login.c
+++ b/login-utils/login.c
@@ -388,9 +388,11 @@ static void init_tty(struct login_context *cxt)
 	}
 
 #ifdef LOGIN_CHOWN_VCS
-	/* find names of Virtual Console devices, for later mode change */
-	snprintf(cxt->vcsn, sizeof(cxt->vcsn), "/dev/vcs%s", cxt->tty_number);
-	snprintf(cxt->vcsan, sizeof(cxt->vcsan), "/dev/vcsa%s", cxt->tty_number);
+	if (cxt->tty_number) {
+		/* find names of Virtual Console devices, for later mode change */
+		snprintf(cxt->vcsn, sizeof(cxt->vcsn), "/dev/vcs%s", cxt->tty_number);
+		snprintf(cxt->vcsan, sizeof(cxt->vcsan), "/dev/vcsa%s", cxt->tty_number);
+	}
 #endif
 
 	tcgetattr(0, &tt);
@@ -577,7 +579,8 @@ static void log_utmp(struct login_context *cxt)
 	if (utp == NULL) {
 		setutent();
 		ut.ut_type = LOGIN_PROCESS;
-		strncpy(ut.ut_line, cxt->tty_name, sizeof(ut.ut_line));
+		if (cxt->tty_name)
+			strncpy(ut.ut_line, cxt->tty_name, sizeof(ut.ut_line));
 		utp = getutline(&ut);
 	}
 
@@ -587,11 +590,12 @@ static void log_utmp(struct login_context *cxt)
 		/* some gettys/telnetds don't initialize utmp... */
 		memset(&ut, 0, sizeof(ut));
 
-	if (ut.ut_id[0] == 0)
+	if (cxt->tty_number && ut.ut_id[0] == 0)
 		strncpy(ut.ut_id, cxt->tty_number, sizeof(ut.ut_id));
-
-	strncpy(ut.ut_user, cxt->username, sizeof(ut.ut_user));
-	xstrncpy(ut.ut_line, cxt->tty_name, sizeof(ut.ut_line));
+	if (cxt->username)
+		strncpy(ut.ut_user, cxt->username, sizeof(ut.ut_user));
+	if (cxt->tty_name)
+		xstrncpy(ut.ut_line, cxt->tty_name, sizeof(ut.ut_line));
 
 #ifdef _HAVE_UT_TV		/* in <utmpbits.h> included by <utmp.h> */
 	gettimeofday(&tv, NULL);
@@ -624,6 +628,9 @@ static void log_syslog(struct login_context *cxt)
 {
 	struct passwd *pwd = cxt->pwd;
 
+	if (!cxt->tty_name)
+		return;
+
 	if (!strncmp(cxt->tty_name, "ttyS", 4))
 		syslog(LOG_INFO, _("DIALUP AT %s BY %s"),
 		       cxt->tty_name, pwd->pw_name);