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authorNicholas Bellinger <nab@linux-iscsi.org>2017-06-02 20:00:17 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2017-06-29 12:48:51 +0200
commitd374be75f4c7e178fc34140ebec3f54f3f72ae15 (patch)
tree943630bee6679179af27b3db5665226d6c60c4c0
parent1fecf3977defb3161ba194e5ddbdeca9be638377 (diff)
downloadlinux-linaro-stable-d374be75f4c7e178fc34140ebec3f54f3f72ae15.tar.gz
target: Fix kref->refcount underflow in transport_cmd_finish_abort
commit 73d4e580ccc5c3e05cea002f18111f66c9c07034 upstream. This patch fixes a se_cmd->cmd_kref underflow during CMD_T_ABORTED when a fabric driver drops it's second reference from below the target_core_tmr.c based callers of transport_cmd_finish_abort(). Recently with the conversion of kref to refcount_t, this bug was manifesting itself as: [705519.601034] refcount_t: underflow; use-after-free. [705519.604034] INFO: NMI handler (kgdb_nmi_handler) took too long to run: 20116.512 msecs [705539.719111] ------------[ cut here ]------------ [705539.719117] WARNING: CPU: 3 PID: 26510 at lib/refcount.c:184 refcount_sub_and_test+0x33/0x51 Since the original kref atomic_t based kref_put() didn't check for underflow and only invoked the final callback when zero was reached, this bug did not manifest in practice since all se_cmd memory is using preallocated tags. To address this, go ahead and propigate the existing return from transport_put_cmd() up via transport_cmd_finish_abort(), and change transport_cmd_finish_abort() + core_tmr_handle_tas_abort() callers to only do their local target_put_sess_cmd() if necessary. Reported-by: Bart Van Assche <bart.vanassche@sandisk.com> Tested-by: Bart Van Assche <bart.vanassche@sandisk.com> Cc: Mike Christie <mchristi@redhat.com> Cc: Hannes Reinecke <hare@suse.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Himanshu Madhani <himanshu.madhani@qlogic.com> Cc: Sagi Grimberg <sagig@mellanox.com> Tested-by: Gary Guo <ghg@datera.io> Tested-by: Chu Yuan Lin <cyl@datera.io> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/target/target_core_internal.h2
-rw-r--r--drivers/target/target_core_tmr.c16
-rw-r--r--drivers/target/target_core_transport.c9
3 files changed, 15 insertions, 12 deletions
diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h
index 253a91bff943..272e6f755322 100644
--- a/drivers/target/target_core_internal.h
+++ b/drivers/target/target_core_internal.h
@@ -132,7 +132,7 @@ int init_se_kmem_caches(void);
void release_se_kmem_caches(void);
u32 scsi_get_new_index(scsi_index_t);
void transport_subsystem_check_init(void);
-void transport_cmd_finish_abort(struct se_cmd *, int);
+int transport_cmd_finish_abort(struct se_cmd *, int);
unsigned char *transport_dump_cmd_direction(struct se_cmd *);
void transport_dump_dev_state(struct se_device *, char *, int *);
void transport_dump_dev_info(struct se_device *, struct se_lun *,
diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index 46b1991fbb50..c9be953496ec 100644
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -75,7 +75,7 @@ void core_tmr_release_req(struct se_tmr_req *tmr)
kfree(tmr);
}
-static void core_tmr_handle_tas_abort(struct se_cmd *cmd, int tas)
+static int core_tmr_handle_tas_abort(struct se_cmd *cmd, int tas)
{
unsigned long flags;
bool remove = true, send_tas;
@@ -91,7 +91,7 @@ static void core_tmr_handle_tas_abort(struct se_cmd *cmd, int tas)
transport_send_task_abort(cmd);
}
- transport_cmd_finish_abort(cmd, remove);
+ return transport_cmd_finish_abort(cmd, remove);
}
static int target_check_cdb_and_preempt(struct list_head *list,
@@ -185,8 +185,8 @@ void core_tmr_abort_task(
cancel_work_sync(&se_cmd->work);
transport_wait_for_tasks(se_cmd);
- transport_cmd_finish_abort(se_cmd, true);
- target_put_sess_cmd(se_cmd);
+ if (!transport_cmd_finish_abort(se_cmd, true))
+ target_put_sess_cmd(se_cmd);
printk("ABORT_TASK: Sending TMR_FUNCTION_COMPLETE for"
" ref_tag: %llu\n", ref_tag);
@@ -286,8 +286,8 @@ static void core_tmr_drain_tmr_list(
cancel_work_sync(&cmd->work);
transport_wait_for_tasks(cmd);
- transport_cmd_finish_abort(cmd, 1);
- target_put_sess_cmd(cmd);
+ if (!transport_cmd_finish_abort(cmd, 1))
+ target_put_sess_cmd(cmd);
}
}
@@ -385,8 +385,8 @@ static void core_tmr_drain_state_list(
cancel_work_sync(&cmd->work);
transport_wait_for_tasks(cmd);
- core_tmr_handle_tas_abort(cmd, tas);
- target_put_sess_cmd(cmd);
+ if (!core_tmr_handle_tas_abort(cmd, tas))
+ target_put_sess_cmd(cmd);
}
}
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 60743bf27f37..37c77db6e737 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -639,9 +639,10 @@ static void transport_lun_remove_cmd(struct se_cmd *cmd)
percpu_ref_put(&lun->lun_ref);
}
-void transport_cmd_finish_abort(struct se_cmd *cmd, int remove)
+int transport_cmd_finish_abort(struct se_cmd *cmd, int remove)
{
bool ack_kref = (cmd->se_cmd_flags & SCF_ACK_KREF);
+ int ret = 0;
if (cmd->se_cmd_flags & SCF_SE_LUN_CMD)
transport_lun_remove_cmd(cmd);
@@ -653,9 +654,11 @@ void transport_cmd_finish_abort(struct se_cmd *cmd, int remove)
cmd->se_tfo->aborted_task(cmd);
if (transport_cmd_check_stop_to_fabric(cmd))
- return;
+ return 1;
if (remove && ack_kref)
- transport_put_cmd(cmd);
+ ret = transport_put_cmd(cmd);
+
+ return ret;
}
static void target_complete_failure_work(struct work_struct *work)