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author | Nicholas Bellinger <nab@linux-iscsi.org> | 2017-06-03 03:00:17 (GMT) |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-06-29 11:00:30 (GMT) |
commit | 1f576d53d854b336affc844c616055b518e53bff (patch) | |
tree | 54629a0c6ba67217459f05f09c13c41db46649fa | |
parent | 99f66b5182a4f3d89563634f2fe156d4629b9c10 (diff) | |
download | linux-1f576d53d854b336affc844c616055b518e53bff.tar.xz |
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.h | 2 | ||||
-rw-r--r-- | drivers/target/target_core_tmr.c | 16 | ||||
-rw-r--r-- | drivers/target/target_core_transport.c | 9 |
3 files changed, 15 insertions, 12 deletions
diff --git a/drivers/target/target_core_internal.h b/drivers/target/target_core_internal.h index e2c970a..be52838 100644 --- a/drivers/target/target_core_internal.h +++ b/drivers/target/target_core_internal.h @@ -131,7 +131,7 @@ 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 4f229e7..27dd1e1 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 077344c..1f9bfa4 100644 --- a/drivers/target/target_core_transport.c +++ b/drivers/target/target_core_transport.c @@ -673,9 +673,10 @@ 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); @@ -687,9 +688,11 @@ 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) |