RDMA/srpt: Fix a use-after-free

Change the LIO port members inside struct srpt_port from regular members
into pointers. Allocate the LIO port data structures from inside
srpt_make_tport() and free these from inside srpt_make_tport(). Keep
struct srpt_device as long as either an RDMA port or a LIO target port is
associated with it. This patch decouples the lifetime of struct srpt_port
(controlled by the RDMA core) and struct srpt_port_id (controlled by LIO).
This patch fixes the following KASAN complaint:

  BUG: KASAN: use-after-free in srpt_enable_tpg+0x31/0x70 [ib_srpt]
  Read of size 8 at addr ffff888141cc34b8 by task check/5093

  Call Trace:
   <TASK>
   show_stack+0x4e/0x53
   dump_stack_lvl+0x51/0x66
   print_address_description.constprop.0.cold+0xea/0x41e
   print_report.cold+0x90/0x205
   kasan_report+0xb9/0xf0
   __asan_load8+0x69/0x90
   srpt_enable_tpg+0x31/0x70 [ib_srpt]
   target_fabric_tpg_base_enable_store+0xe2/0x140 [target_core_mod]
   configfs_write_iter+0x18b/0x210
   new_sync_write+0x1f2/0x2f0
   vfs_write+0x3e3/0x540
   ksys_write+0xbb/0x140
   __x64_sys_write+0x42/0x50
   do_syscall_64+0x34/0x80
   entry_SYSCALL_64_after_hwframe+0x46/0xb0
   </TASK>

Link: https://lore.kernel.org/r/20220727193415.1583860-4-bvanassche@acm.org
Reported-by: Li Zhijian <lizhijian@fujitsu.com>
Tested-by: Li Zhijian <lizhijian@fujitsu.com>
Fixes: a42d985bd5b2 ("ib_srpt: Initial SRP Target merge for v3.3-rc1")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>

diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.c b/drivers/infiniband/ulp/srpt/ib_srpt.c
index 1fbce92..c3036ae 100644 (file)
--- a/drivers/infiniband/ulp/srpt/ib_srpt.c
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.c
@@ -565,18 +565,12 @@ static int srpt_refresh_port(struct srpt_port *sport)
        if (ret)
                return ret;
 
-       sport->port_guid_id.wwn.priv = sport;
        srpt_format_guid(sport->guid_name, ARRAY_SIZE(sport->guid_name),
                         &sport->gid.global.interface_id);
-       memcpy(sport->port_guid_id.name, sport->guid_name,
-              ARRAY_SIZE(sport->guid_name));
-       sport->port_gid_id.wwn.priv = sport;
        snprintf(sport->gid_name, ARRAY_SIZE(sport->gid_name),
                 "0x%016llx%016llx",
                 be64_to_cpu(sport->gid.global.subnet_prefix),
                 be64_to_cpu(sport->gid.global.interface_id));
-       memcpy(sport->port_gid_id.name, sport->gid_name,
-              ARRAY_SIZE(sport->gid_name));
 
        if (rdma_protocol_iwarp(sport->sdev->device, sport->port))
                return 0;
@@ -2317,31 +2311,35 @@ static int srpt_cm_req_recv(struct srpt_device *const sdev,
        tag_num = ch->rq_size;
        tag_size = 1; /* ib_srpt does not use se_sess->sess_cmd_map */
 
-       mutex_lock(&sport->port_guid_id.mutex);
-       list_for_each_entry(stpg, &sport->port_guid_id.tpg_list, entry) {
-               if (!IS_ERR_OR_NULL(ch->sess))
-                       break;
-               ch->sess = target_setup_session(&stpg->tpg, tag_num,
+       if (sport->guid_id) {
+               mutex_lock(&sport->guid_id->mutex);
+               list_for_each_entry(stpg, &sport->guid_id->tpg_list, entry) {
+                       if (!IS_ERR_OR_NULL(ch->sess))
+                               break;
+                       ch->sess = target_setup_session(&stpg->tpg, tag_num,
                                                tag_size, TARGET_PROT_NORMAL,
                                                ch->sess_name, ch, NULL);
+               }
+               mutex_unlock(&sport->guid_id->mutex);
        }
-       mutex_unlock(&sport->port_guid_id.mutex);
 
-       mutex_lock(&sport->port_gid_id.mutex);
-       list_for_each_entry(stpg, &sport->port_gid_id.tpg_list, entry) {
-               if (!IS_ERR_OR_NULL(ch->sess))
-                       break;
-               ch->sess = target_setup_session(&stpg->tpg, tag_num,
+       if (sport->gid_id) {
+               mutex_lock(&sport->gid_id->mutex);
+               list_for_each_entry(stpg, &sport->gid_id->tpg_list, entry) {
+                       if (!IS_ERR_OR_NULL(ch->sess))
+                               break;
+                       ch->sess = target_setup_session(&stpg->tpg, tag_num,
                                        tag_size, TARGET_PROT_NORMAL, i_port_id,
                                        ch, NULL);
-               if (!IS_ERR_OR_NULL(ch->sess))
-                       break;
-               /* Retry without leading "0x" */
-               ch->sess = target_setup_session(&stpg->tpg, tag_num,
+                       if (!IS_ERR_OR_NULL(ch->sess))
+                               break;
+                       /* Retry without leading "0x" */
+                       ch->sess = target_setup_session(&stpg->tpg, tag_num,
                                                tag_size, TARGET_PROT_NORMAL,
                                                i_port_id + 2, ch, NULL);
+               }
+               mutex_unlock(&sport->gid_id->mutex);
        }
-       mutex_unlock(&sport->port_gid_id.mutex);
 
        if (IS_ERR_OR_NULL(ch->sess)) {
                WARN_ON_ONCE(ch->sess == NULL);
@@ -2986,7 +2984,12 @@ static int srpt_release_sport(struct srpt_port *sport)
        return 0;
 }
 
-static struct se_wwn *__srpt_lookup_wwn(const char *name)
+struct port_and_port_id {
+       struct srpt_port *sport;
+       struct srpt_port_id **port_id;
+};
+
+static struct port_and_port_id __srpt_lookup_port(const char *name)
 {
        struct ib_device *dev;
        struct srpt_device *sdev;
@@ -3001,25 +3004,38 @@ static struct se_wwn *__srpt_lookup_wwn(const char *name)
                for (i = 0; i < dev->phys_port_cnt; i++) {
                        sport = &sdev->port[i];
 
-                       if (strcmp(sport->port_guid_id.name, name) == 0)
-                               return &sport->port_guid_id.wwn;
-                       if (strcmp(sport->port_gid_id.name, name) == 0)
-                               return &sport->port_gid_id.wwn;
+                       if (strcmp(sport->guid_name, name) == 0) {
+                               kref_get(&sdev->refcnt);
+                               return (struct port_and_port_id){
+                                       sport, &sport->guid_id};
+                       }
+                       if (strcmp(sport->gid_name, name) == 0) {
+                               kref_get(&sdev->refcnt);
+                               return (struct port_and_port_id){
+                                       sport, &sport->gid_id};
+                       }
                }
        }
 
-       return NULL;
+       return (struct port_and_port_id){};
 }
 
-static struct se_wwn *srpt_lookup_wwn(const char *name)
+/**
+ * srpt_lookup_port() - Look up an RDMA port by name
+ * @name: ASCII port name
+ *
+ * Increments the RDMA port reference count if an RDMA port pointer is returned.
+ * The caller must drop that reference count by calling srpt_port_put_ref().
+ */
+static struct port_and_port_id srpt_lookup_port(const char *name)
 {
-       struct se_wwn *wwn;
+       struct port_and_port_id papi;
 
        spin_lock(&srpt_dev_lock);
-       wwn = __srpt_lookup_wwn(name);
+       papi = __srpt_lookup_port(name);
        spin_unlock(&srpt_dev_lock);
 
-       return wwn;
+       return papi;
 }
 
 static void srpt_free_srq(struct srpt_device *sdev)
@@ -3198,10 +3214,6 @@ static int srpt_add_one(struct ib_device *device)
                sport->port_attrib.srp_sq_size = DEF_SRPT_SQ_SIZE;
                sport->port_attrib.use_srq = false;
                INIT_WORK(&sport->work, srpt_refresh_port_work);
-               mutex_init(&sport->port_guid_id.mutex);
-               INIT_LIST_HEAD(&sport->port_guid_id.tpg_list);
-               mutex_init(&sport->port_gid_id.mutex);
-               INIT_LIST_HEAD(&sport->port_gid_id.tpg_list);
 
                ret = srpt_refresh_port(sport);
                if (ret) {
@@ -3302,10 +3314,10 @@ static struct srpt_port_id *srpt_wwn_to_sport_id(struct se_wwn *wwn)
 {
        struct srpt_port *sport = wwn->priv;
 
-       if (wwn == &sport->port_guid_id.wwn)
-               return &sport->port_guid_id;
-       if (wwn == &sport->port_gid_id.wwn)
-               return &sport->port_gid_id;
+       if (sport->guid_id && &sport->guid_id->wwn == wwn)
+               return sport->guid_id;
+       if (sport->gid_id && &sport->gid_id->wwn == wwn)
+               return sport->gid_id;
        WARN_ON_ONCE(true);
        return NULL;
 }
@@ -3790,7 +3802,31 @@ static struct se_wwn *srpt_make_tport(struct target_fabric_configfs *tf,
                                      struct config_group *group,
                                      const char *name)
 {
-       return srpt_lookup_wwn(name) ? : ERR_PTR(-EINVAL);
+       struct port_and_port_id papi = srpt_lookup_port(name);
+       struct srpt_port *sport = papi.sport;
+       struct srpt_port_id *port_id;
+
+       if (!papi.port_id)
+               return ERR_PTR(-EINVAL);
+       if (*papi.port_id) {
+               /* Attempt to create a directory that already exists. */
+               WARN_ON_ONCE(true);
+               return &(*papi.port_id)->wwn;
+       }
+       port_id = kzalloc(sizeof(*port_id), GFP_KERNEL);
+       if (!port_id) {
+               srpt_sdev_put(sport->sdev);
+               return ERR_PTR(-ENOMEM);
+       }
+       mutex_init(&port_id->mutex);
+       INIT_LIST_HEAD(&port_id->tpg_list);
+       port_id->wwn.priv = sport;
+       memcpy(port_id->name, port_id == sport->guid_id ? sport->guid_name :
+              sport->gid_name, ARRAY_SIZE(port_id->name));
+
+       *papi.port_id = port_id;
+
+       return &port_id->wwn;
 }
 
 /**
@@ -3799,6 +3835,18 @@ static struct se_wwn *srpt_make_tport(struct target_fabric_configfs *tf,
  */
 static void srpt_drop_tport(struct se_wwn *wwn)
 {
+       struct srpt_port_id *port_id = container_of(wwn, typeof(*port_id), wwn);
+       struct srpt_port *sport = wwn->priv;
+
+       if (sport->guid_id == port_id)
+               sport->guid_id = NULL;
+       else if (sport->gid_id == port_id)
+               sport->gid_id = NULL;
+       else
+               WARN_ON_ONCE(true);
+
+       srpt_sdev_put(sport->sdev);
+       kfree(port_id);
 }
 
 static ssize_t srpt_wwn_version_show(struct config_item *item, char *buf)

diff --git a/drivers/infiniband/ulp/srpt/ib_srpt.h b/drivers/infiniband/ulp/srpt/ib_srpt.h
index 0cb867d..4c46b30 100644 (file)
--- a/drivers/infiniband/ulp/srpt/ib_srpt.h
+++ b/drivers/infiniband/ulp/srpt/ib_srpt.h
@@ -393,7 +393,7 @@ struct srpt_port_id {
 };
 
 /**
- * struct srpt_port - information associated by SRPT with a single IB port
+ * struct srpt_port - SRPT RDMA port information
  * @sdev:      backpointer to the HCA information.
  * @mad_agent: per-port management datagram processing information.
  * @enabled:   Whether or not this target port is enabled.
@@ -403,9 +403,9 @@ struct srpt_port_id {
  * @gid:       cached value of the port's gid.
  * @work:      work structure for refreshing the aforementioned cached values.
  * @guid_name: port name in GUID format.
- * @port_guid_id: LIO target port information for the port name in GUID format.
+ * @guid_id:   LIO target port information for the port name in GUID format.
  * @gid_name:  port name in GID format.
- * @port_gid_id: LIO target port information for the port name in GID format.
+ * @gid_id:    LIO target port information for the port name in GID format.
  * @port_attrib:   Port attributes that can be accessed through configfs.
  * @refcount:     Number of objects associated with this port.
  * @freed_channels: Completion that will be signaled once @refcount becomes 0.
@@ -422,9 +422,9 @@ struct srpt_port {
        union ib_gid            gid;
        struct work_struct      work;
        char                    guid_name[64];
-       struct srpt_port_id     port_guid_id;
+       struct srpt_port_id     *guid_id;
        char                    gid_name[64];
-       struct srpt_port_id     port_gid_id;
+       struct srpt_port_id     *gid_id;
        struct srpt_port_attrib port_attrib;
        atomic_t                refcount;
        struct completion       *freed_channels;