sunrpc: clean up properly in gss_mech_unregister()

gss_mech_register() calls svcauth_gss_register_pseudoflavor() for each
flavour, but gss_mech_unregister() does not call auth_domain_put().
This is unbalanced and makes it impossible to reload the module.

Change svcauth_gss_register_pseudoflavor() to return the registered
auth_domain, and save it for later release.

Cc: stable@vger.kernel.org (v2.6.12+)
Link: https://bugzilla.kernel.org/show_bug.cgi?id=206651
Signed-off-by: NeilBrown <neilb@suse.de>
Signed-off-by: J. Bruce Fields <bfields@redhat.com>

include/linux/sunrpc/gss_api.h

@@ -84,6 +84,7 @@ struct pf_desc {
 	u32	service;
 	char	*name;
 	char	*auth_domain_name;
+	struct auth_domain *domain;
 	bool	datatouch;
 };
 

include/linux/sunrpc/svcauth_gss.h

@@ -20,7 +20,8 @@ int gss_svc_init(void);
 void gss_svc_shutdown(void);
 int gss_svc_init_net(struct net *net);
 void gss_svc_shutdown_net(struct net *net);
-int svcauth_gss_register_pseudoflavor(u32 pseudoflavor, char * name);
+struct auth_domain *svcauth_gss_register_pseudoflavor(u32 pseudoflavor,
+						      char *name);
 u32 svcauth_gss_flavor(struct auth_domain *dom);
 
 #endif /* _LINUX_SUNRPC_SVCAUTH_GSS_H */

net/sunrpc/auth_gss/gss_mech_switch.c

@@ -37,6 +37,8 @@ gss_mech_free(struct gss_api_mech *gm)
 
 	for (i = 0; i < gm->gm_pf_num; i++) {
 		pf = &gm->gm_pfs[i];
+		if (pf->domain)
+			auth_domain_put(pf->domain);
 		kfree(pf->auth_domain_name);
 		pf->auth_domain_name = NULL;
 	}
@@ -59,6 +61,7 @@ make_auth_domain_name(char *name)
 static int
 gss_mech_svc_setup(struct gss_api_mech *gm)
 {
+	struct auth_domain *dom;
 	struct pf_desc *pf;
 	int i, status;
 
@@ -68,10 +71,13 @@ gss_mech_svc_setup(struct gss_api_mech *gm)
 		status = -ENOMEM;
 		if (pf->auth_domain_name == NULL)
 			goto out;
-		status = svcauth_gss_register_pseudoflavor(pf->pseudoflavor,
-							pf->auth_domain_name);
-		if (status)
+		dom = svcauth_gss_register_pseudoflavor(
+			pf->pseudoflavor, pf->auth_domain_name);
+		if (IS_ERR(dom)) {
+			status = PTR_ERR(dom);
 			goto out;
+		}
+		pf->domain = dom;
 	}
 	return 0;
 out:

net/sunrpc/auth_gss/svcauth_gss.c

@@ -809,7 +809,7 @@ u32 svcauth_gss_flavor(struct auth_domain *dom)
 
 EXPORT_SYMBOL_GPL(svcauth_gss_flavor);
 
-int
+struct auth_domain *
 svcauth_gss_register_pseudoflavor(u32 pseudoflavor, char * name)
 {
 	struct gss_domain	*new;
@@ -832,17 +832,17 @@ svcauth_gss_register_pseudoflavor(u32 pseudoflavor, char * name)
 			name);
 		stat = -EADDRINUSE;
 		auth_domain_put(test);
-		kfree(new->h.name);
-		goto out_free_dom;
+		goto out_free_name;
 	}
-	return 0;
+	return test;
 
+out_free_name:
+	kfree(new->h.name);
 out_free_dom:
 	kfree(new);
 out:
-	return stat;
+	return ERR_PTR(stat);
 }
-
 EXPORT_SYMBOL_GPL(svcauth_gss_register_pseudoflavor);
 
 static inline int