8 files changed, 25 insertions, 27 deletions

diff --git a/auth-pam.c b/auth-pam.c
index 15a691b11..d3186372e 100644
--- a/auth-pam.c
+++ b/auth-pam.c
@@ -160,7 +160,7 @@ static int sshpam_session_open = 0;
 static int sshpam_cred_established = 0;
 static int sshpam_account_status = -1;
 static char **sshpam_env = NULL;
-static int *force_pwchange;
+static Authctxt *the_authctxt = NULL;
 
 /* Some PAM implementations don't implement this */
 #ifndef HAVE_PAM_GETENVLIST
@@ -180,7 +180,9 @@ void
 pam_password_change_required(int reqd)
 {
         debug3("%s %d", __func__, reqd);
-        *force_pwchange = reqd;
+        if (the_authctxt == NULL)
+                fatal("%s: PAM authctxt not initialized", __func__);
+        the_authctxt->force_pwchange = reqd;
         if (reqd) {
                 no_port_forwarding_flag |= 2;
                 no_agent_forwarding_flag |= 2;
@@ -337,6 +339,9 @@ sshpam_thread(void *ctxtp)
         sshpam_conv.conv = sshpam_thread_conv;
         sshpam_conv.appdata_ptr = ctxt;
 
+        if (the_authctxt == NULL)
+                fatal("%s: PAM authctxt not initialized", __func__);
+
         buffer_init(&buffer);
         sshpam_err = pam_set_item(sshpam_handle, PAM_CONV,
             (const void *)&sshpam_conv);
@@ -349,7 +354,7 @@ sshpam_thread(void *ctxtp)
         if (compat20) {
                 if (!do_pam_account())
                         goto auth_fail;
-                if (*force_pwchange) {
+                if (the_authctxt->force_pwchange) {
                         sshpam_err = pam_chauthtok(sshpam_handle,
                             PAM_CHANGE_EXPIRED_AUTHTOK);
                         if (sshpam_err != PAM_SUCCESS)
@@ -363,7 +368,7 @@ sshpam_thread(void *ctxtp)
 #ifndef USE_POSIX_THREADS
         /* Export variables set by do_pam_account */
         buffer_put_int(&buffer, sshpam_account_status);
-        buffer_put_int(&buffer, *force_pwchange);
+        buffer_put_int(&buffer, the_authctxt->force_pwchange);
 
         /* Export any environment strings set in child */
         for(i = 0; environ[i] != NULL; i++)
@@ -444,11 +449,11 @@ sshpam_cleanup(void)
 }
 
 static int
-sshpam_init(const char *user)
+sshpam_init(Authctxt *authctxt)
 {
         extern u_int utmp_len;
         extern char *__progname;
-        const char *pam_rhost, *pam_user;
+        const char *pam_rhost, *pam_user, *user = authctxt->user;
 
         if (sshpam_handle != NULL) {
                 /* We already have a PAM context; check if the user matches */
@@ -462,6 +467,8 @@ sshpam_init(const char *user)
         debug("PAM: initializing for \"%s\"", user);
         sshpam_err =
             pam_start(SSHD_PAM_SERVICE, user, &null_conv, &sshpam_handle);
+        the_authctxt = authctxt;
+
         if (sshpam_err != PAM_SUCCESS) {
                 pam_end(sshpam_handle, sshpam_err);
                 sshpam_handle = NULL;
@@ -504,7 +511,7 @@ sshpam_init_ctx(Authctxt *authctxt)
                 return NULL;
 
         /* Initialize PAM */
-        if (sshpam_init(authctxt->user) == -1) {
+        if (sshpam_init(authctxt) == -1) {
                 error("PAM: initialization failed");
                 return (NULL);
         }
@@ -512,8 +519,6 @@ sshpam_init_ctx(Authctxt *authctxt)
         ctxt = xmalloc(sizeof *ctxt);
         memset(ctxt, 0, sizeof(*ctxt));
 
-        force_pwchange = &(authctxt->force_pwchange);
-
         /* Start the authentication thread */
         if (socketpair(AF_UNIX, SOCK_STREAM, PF_UNSPEC, socks) == -1) {
                 error("PAM: failed create sockets: %s", strerror(errno));
@@ -672,12 +677,12 @@ KbdintDevice mm_sshpam_device = {
  * This replaces auth-pam.c
  */
 void
-start_pam(const char *user)
+start_pam(Authctxt *authctxt)
 {
         if (!options.use_pam)
                 fatal("PAM: initialisation requested when UsePAM=no");
 
-        if (sshpam_init(user) == -1)
+        if (sshpam_init(authctxt) == -1)
                 fatal("PAM: initialisation failed");
 }
 
diff --git a/auth-pam.h b/auth-pam.h
index 4bc8d6955..f3aad063b 100644
--- a/auth-pam.h
+++ b/auth-pam.h
@@ -31,7 +31,7 @@
 # define SSHD_PAM_SERVICE               __progname
 #endif
 
-void start_pam(const char *);
+void start_pam(Authctxt *);
 void finish_pam(void);
 u_int do_pam_account(void);
 void do_pam_session(void);
diff --git a/auth1.c b/auth1.c
index 82fe5fb80..f145cf03d 100644
--- a/auth1.c
+++ b/auth1.c
@@ -307,7 +307,7 @@ do_authentication(Authctxt *authctxt)
 
 #ifdef USE_PAM
         if (options.use_pam)
-                PRIVSEP(start_pam(user));
+                PRIVSEP(start_pam(authctxt));
 #endif
 
         /*
diff --git a/auth2.c b/auth2.c
index a9490ccfd..1177efa73 100644
--- a/auth2.c
+++ b/auth2.c
@@ -150,24 +150,24 @@ input_userauth_request(int type, u_int32_t seq, void *ctxt)
         if (authctxt->attempt++ == 0) {
                 /* setup auth context */
                 authctxt->pw = PRIVSEP(getpwnamallow(user));
+                authctxt->user = xstrdup(user);
                 if (authctxt->pw && strcmp(service, "ssh-connection")==0) {
                         authctxt->valid = 1;
                         debug2("input_userauth_request: setting up authctxt for %s", user);
 #ifdef USE_PAM
                         if (options.use_pam)
-                                PRIVSEP(start_pam(authctxt->pw->pw_name));
+                                PRIVSEP(start_pam(authctxt));
 #endif
                 } else {
                         logit("input_userauth_request: illegal user %s", user);
                         authctxt->pw = fakepw();
 #ifdef USE_PAM
                         if (options.use_pam)
-                                PRIVSEP(start_pam(user));
+                                PRIVSEP(start_pam(authctxt));
 #endif
                 }
                 setproctitle("%s%s", authctxt->pw ? user : "unknown",
                     use_privsep ? " [net]" : "");
-                authctxt->user = xstrdup(user);
                 authctxt->service = xstrdup(service);
                 authctxt->style = style ? xstrdup(style) : NULL;
                 if (use_privsep)
diff --git a/debian/changelog b/debian/changelog
index 2bb0f227a..4e4ca2fb4 100644
--- a/debian/changelog
+++ b/debian/changelog
@@ -27,6 +27,7 @@ openssh (1:3.8p1-1) UNRELEASED; urgency=low
   * Darren Tucker:
     - Reset signal status when starting pam auth thread, prevent hanging
       during PAM keyboard-interactive authentications.
+    - Fix a non-security-critical segfault in PAM authentication.
 
  -- Colin Watson <cjwatson@debian.org>  Tue, 23 Sep 2003 19:22:38 +0100
 
diff --git a/monitor.c b/monitor.c
index 009dcf182..30f7258a0 100644
--- a/monitor.c
+++ b/monitor.c
@@ -782,16 +782,10 @@ mm_answer_skeyrespond(int socket, Buffer *m)
 int
 mm_answer_pam_start(int socket, Buffer *m)
 {
-        char *user;
-
         if (!options.use_pam)
                 fatal("UsePAM not set, but ended up in %s anyway", __func__);
 
-        user = buffer_get_string(m, NULL);
-
-        start_pam(user);
-
-        xfree(user);
+        start_pam(authctxt);
 
         monitor_permit(mon_dispatch, MONITOR_REQ_PAM_ACCOUNT, 1);
 
diff --git a/monitor_wrap.c b/monitor_wrap.c
index e7c15cecd..b1b1c3a61 100644
--- a/monitor_wrap.c
+++ b/monitor_wrap.c
@@ -686,7 +686,7 @@ mm_session_pty_cleanup2(Session *s)
 
 #ifdef USE_PAM
 void
-mm_start_pam(char *user)
+mm_start_pam(Authctxt *authctxt)
 {
         Buffer m;
 
@@ -695,8 +695,6 @@ mm_start_pam(char *user)
                 fatal("UsePAM=no, but ended up in %s anyway", __func__);
 
         buffer_init(&m);
-        buffer_put_cstring(&m, user);
-
         mm_request_send(pmonitor->m_recvfd, MONITOR_REQ_PAM_START, &m);
 
         buffer_free(&m);
diff --git a/monitor_wrap.h b/monitor_wrap.h
index 55be10b19..2170b1324 100644
--- a/monitor_wrap.h
+++ b/monitor_wrap.h
@@ -66,7 +66,7 @@ OM_uint32 mm_ssh_gssapi_checkmic(Gssctxt *, gss_buffer_t, gss_buffer_t);
 #endif
 
 #ifdef USE_PAM
-void mm_start_pam(char *);
+void mm_start_pam(struct Authctxt *);
 u_int mm_do_pam_account(void);
 void *mm_sshpam_init_ctx(struct Authctxt *);
 int mm_sshpam_query(void *, char **, char **, u_int *, char ***, u_int **);