Messages in this thread Patch in this message | | | From | Greg Kroah-Hartman <> | Subject | [PATCH 4.9 29/60] target: Fix COMPARE_AND_WRITE ref leak for non GOOD status | Date | Mon, 13 Feb 2017 05:04:01 -0800 |
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4.9-stable review patch. If anyone has any objections, please let me know.
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From: Nicholas Bellinger <nab@linux-iscsi.org>
commit 9b2792c3da1e80f2d460167d319302a24c9ca2b7 upstream.
This patch addresses a long standing bug where the commit phase of COMPARE_AND_WRITE would result in a se_cmd->cmd_kref reference leak if se_cmd->scsi_status returned non SAM_STAT_GOOD.
This would manifest first as a lost SCSI response, and eventual hung task during fabric driver logout or re-login, as existing shutdown logic waited for the COMPARE_AND_WRITE se_cmd->cmd_kref to reach zero.
To address this bug, compare_and_write_post() has been changed to drop the incorrect !cmd->scsi_status conditional that was preventing *post_ret = 1 for being set during non SAM_STAT_GOOD status.
This patch has been tested with SAM_STAT_CHECK_CONDITION status from normal target_complete_cmd() callback path, as well as the incoming __target_execute_cmd() submission failure path when se_cmd->execute_cmd() returns non zero status.
Reported-by: Donald White <dew@datera.io> Cc: Donald White <dew@datera.io> Tested-by: Gary Guo <ghg@datera.io> Cc: Gary Guo <ghg@datera.io> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/target/target_core_sbc.c | 8 ++++++-- 1 file changed, 6 insertions(+), 2 deletions(-)
--- a/drivers/target/target_core_sbc.c +++ b/drivers/target/target_core_sbc.c @@ -450,6 +450,7 @@ static sense_reason_t compare_and_write_ int *post_ret) { struct se_device *dev = cmd->se_dev; + sense_reason_t ret = TCM_NO_SENSE; /* * Only set SCF_COMPARE_AND_WRITE_POST to force a response fall-through @@ -457,9 +458,12 @@ static sense_reason_t compare_and_write_ * sent to the backend driver. */ spin_lock_irq(&cmd->t_state_lock); - if ((cmd->transport_state & CMD_T_SENT) && !cmd->scsi_status) { + if (cmd->transport_state & CMD_T_SENT) { cmd->se_cmd_flags |= SCF_COMPARE_AND_WRITE_POST; *post_ret = 1; + + if (cmd->scsi_status == SAM_STAT_CHECK_CONDITION) + ret = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE; } spin_unlock_irq(&cmd->t_state_lock); @@ -469,7 +473,7 @@ static sense_reason_t compare_and_write_ */ up(&dev->caw_sem); - return TCM_NO_SENSE; + return ret; } static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool success,
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