From patchwork Tue Feb 7 13:17:49 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [4/5] target: Fix multi-session dynamic se_node_acl double free OOPs From: "Nicholas A. Bellinger" X-Patchwork-Id: 9560081 Message-Id: <1486473470-15837-5-git-send-email-nab@linux-iscsi.org> To: target-devel Cc: linux-scsi , lkml , Nicholas Bellinger , Rob Millner Date: Tue, 7 Feb 2017 13:17:49 +0000 From: Nicholas Bellinger This patch addresses a long-standing bug with multi-session (eg: iscsi-target + iser-target) se_node_acl dynamic free withini transport_deregister_session(). This bug is caused when a storage endpoint is configured with demo-mode (generate_node_acls = 1 + cache_dynamic_acls = 1) initiators, and initiator login creates a new dynamic node acl and attaches two sessions to it. After that, demo-mode for the storage instance is disabled via configfs (generate_node_acls = 0 + cache_dynamic_acls = 0) and the existing dynamic acl is never converted to an explicit ACL. The end result is dynamic acl resources are released twice when the sessions are shutdown in transport_deregister_session(). If the storage instance is not changed to disable demo-mode, or the dynamic acl is converted to an explict ACL, or there is only a single session associated with the dynamic ACL, the bug is not triggered. To address this big, move the release of dynamic se_node_acl memory into target_complete_nacl() so it's only freed once when se_node_acl->acl_kref reaches zero. Reported-by: Rob Millner Tested-by: Rob Millner Cc: Rob Millner Cc: stable@vger.kernel.org # 3.10+ Signed-off-by: Nicholas Bellinger --- drivers/target/target_core_tpg.c | 4 +- drivers/target/target_core_transport.c | 69 +++++++++++++++++++++------------- include/target/target_core_base.h | 1 + 3 files changed, 46 insertions(+), 28 deletions(-) diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c index d99752c..4f32c49 100644 --- a/drivers/target/target_core_tpg.c +++ b/drivers/target/target_core_tpg.c @@ -364,7 +364,7 @@ void core_tpg_del_initiator_node_acl(struct se_node_acl *acl) mutex_lock(&tpg->acl_node_mutex); if (acl->dynamic_node_acl) acl->dynamic_node_acl = 0; - list_del(&acl->acl_list); + list_del_init(&acl->acl_list); mutex_unlock(&tpg->acl_node_mutex); target_shutdown_sessions(acl); @@ -540,7 +540,7 @@ int core_tpg_deregister(struct se_portal_group *se_tpg) * in transport_deregister_session(). */ list_for_each_entry_safe(nacl, nacl_tmp, &node_list, acl_list) { - list_del(&nacl->acl_list); + list_del_init(&nacl->acl_list); core_tpg_wait_for_nacl_pr_ref(nacl); core_free_device_list_for_node(nacl, se_tpg); diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c index 8b69843..bd62dd4 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -457,8 +457,20 @@ static void target_complete_nacl(struct kref *kref) { struct se_node_acl *nacl = container_of(kref, struct se_node_acl, acl_kref); + struct se_portal_group *se_tpg = nacl->se_tpg; - complete(&nacl->acl_free_comp); + if (!nacl->dynamic_stop) { + complete(&nacl->acl_free_comp); + return; + } + + mutex_lock(&se_tpg->acl_node_mutex); + list_del_init(&nacl->acl_list); + mutex_unlock(&se_tpg->acl_node_mutex); + + core_tpg_wait_for_nacl_pr_ref(nacl); + core_free_device_list_for_node(nacl, se_tpg); + kfree(nacl); } void target_put_nacl(struct se_node_acl *nacl) @@ -499,12 +511,39 @@ void transport_deregister_session_configfs(struct se_session *se_sess) void transport_free_session(struct se_session *se_sess) { struct se_node_acl *se_nacl = se_sess->se_node_acl; + /* * Drop the se_node_acl->nacl_kref obtained from within * core_tpg_get_initiator_node_acl(). */ if (se_nacl) { + struct se_portal_group *se_tpg = se_nacl->se_tpg; + const struct target_core_fabric_ops *se_tfo = se_tpg->se_tpg_tfo; + unsigned long flags; + se_sess->se_node_acl = NULL; + + /* + * Also determine if we need to drop the extra ->cmd_kref if + * it had been previously dynamically generated, and + * the endpoint is not caching dynamic ACLs. + */ + mutex_lock(&se_tpg->acl_node_mutex); + if (se_nacl->dynamic_node_acl && + !se_tfo->tpg_check_demo_mode_cache(se_tpg)) { + spin_lock_irqsave(&se_nacl->nacl_sess_lock, flags); + if (list_empty(&se_nacl->acl_sess_list)) + se_nacl->dynamic_stop = true; + spin_unlock_irqrestore(&se_nacl->nacl_sess_lock, flags); + + if (se_nacl->dynamic_stop) + list_del_init(&se_nacl->acl_list); + } + mutex_unlock(&se_tpg->acl_node_mutex); + + if (se_nacl->dynamic_stop) + target_put_nacl(se_nacl); + target_put_nacl(se_nacl); } if (se_sess->sess_cmd_map) { @@ -518,16 +557,12 @@ void transport_free_session(struct se_session *se_sess) void transport_deregister_session(struct se_session *se_sess) { struct se_portal_group *se_tpg = se_sess->se_tpg; - const struct target_core_fabric_ops *se_tfo; - struct se_node_acl *se_nacl; unsigned long flags; - bool drop_nacl = false; if (!se_tpg) { transport_free_session(se_sess); return; } - se_tfo = se_tpg->se_tpg_tfo; spin_lock_irqsave(&se_tpg->session_lock, flags); list_del(&se_sess->sess_list); @@ -535,33 +570,15 @@ void transport_deregister_session(struct se_session *se_sess) se_sess->fabric_sess_ptr = NULL; spin_unlock_irqrestore(&se_tpg->session_lock, flags); - /* - * Determine if we need to do extra work for this initiator node's - * struct se_node_acl if it had been previously dynamically generated. - */ - se_nacl = se_sess->se_node_acl; - - mutex_lock(&se_tpg->acl_node_mutex); - if (se_nacl && se_nacl->dynamic_node_acl) { - if (!se_tfo->tpg_check_demo_mode_cache(se_tpg)) { - list_del(&se_nacl->acl_list); - drop_nacl = true; - } - } - mutex_unlock(&se_tpg->acl_node_mutex); - - if (drop_nacl) { - core_tpg_wait_for_nacl_pr_ref(se_nacl); - core_free_device_list_for_node(se_nacl, se_tpg); - se_sess->se_node_acl = NULL; - kfree(se_nacl); - } pr_debug("TARGET_CORE[%s]: Deregistered fabric_sess\n", se_tpg->se_tpg_tfo->get_fabric_name()); /* * If last kref is dropping now for an explicit NodeACL, awake sleeping * ->acl_free_comp caller to wakeup configfs se_node_acl->acl_group * removal context from within transport_free_session() code. + * + * For dynamic ACL, target_put_nacl() uses target_complete_nacl() + * to release all remaining generate_node_acl=1 created ACL resources. */ transport_free_session(se_sess); diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h index 43edf82..da854fb 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -538,6 +538,7 @@ struct se_node_acl { char initiatorname[TRANSPORT_IQN_LEN]; /* Used to signal demo mode created ACL, disabled by default */ bool dynamic_node_acl; + bool dynamic_stop; u32 queue_depth; u32 acl_index; enum target_prot_type saved_prot_type;