linux-kernel - [PATCH] ata: fix a race condition when internal cmd time out

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Date:   Sat, 16 Feb 2019 11:42:57 +0800
From:   Jason Yan <yanaijie@...wei.com>
To:     <linux-ide@...r.kernel.org>, <tj@...nel.org>, <axboe@...nel.dk>,
        <linux-kernel@...r.kernel.org>
CC:     Jason Yan <yanaijie@...wei.com>
Subject: [PATCH] ata: fix a race condition when internal cmd time out

For internal cmds, we will unmap DMA memory associated with the cmd
before we abort the cmd. If DMA transfering data before the aborting,
bus error will occured.

ata_exec_internal_sg
  ->ata_port_freeze if timeout
    ->ata_qc_complete
      ->ata_sg_clean
                                      dma transfering data = bus error
  ->ap->ops->post_internal_cmd
    ->sas_ata_post_internal
      ->sas_ata_internal_abort
        ->abort the cmd

Fix this by move post_internal_cmd() before unmapping the DMA memory
when time out. Notice that we have to set ATA_QCFLAG_FAILED flag before
calling post_internal_cmd() so that the aborting will work.

Reported-by: luojian <luojian5@...wei.com>
Signed-off-by: Jason Yan <yanaijie@...wei.com>
---
 drivers/ata/libata-core.c | 14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

diff --git a/drivers/ata/libata-core.c b/drivers/ata/libata-core.c
index adf28788cab5..d0ff5711e805 100644
--- a/drivers/ata/libata-core.c
+++ b/drivers/ata/libata-core.c
@@ -1665,6 +1665,13 @@ unsigned ata_exec_internal_sg(struct ata_device *dev,
 		 */
 		if (qc->flags & ATA_QCFLAG_ACTIVE) {
 			qc->err_mask |= AC_ERR_TIMEOUT;
+			qc->flags |= ATA_QCFLAG_FAILED;
+
+			spin_unlock_irqrestore(ap->lock, flags);
+			/* do post_internal_cmd */
+			if (ap->ops->post_internal_cmd)
+				ap->ops->post_internal_cmd(qc);
+			spin_lock_irqsave(ap->lock, flags);
 
 			if (ap->ops->error_handler)
 				ata_port_freeze(ap);
@@ -1679,9 +1686,10 @@ unsigned ata_exec_internal_sg(struct ata_device *dev,
 		spin_unlock_irqrestore(ap->lock, flags);
 	}
 
-	/* do post_internal_cmd */
-	if (ap->ops->post_internal_cmd)
-		ap->ops->post_internal_cmd(qc);
+	if (!(qc->err_mask & AC_ERR_TIMEOUT))
+		/* do post_internal_cmd */
+		if (ap->ops->post_internal_cmd)
+			ap->ops->post_internal_cmd(qc);
 
 	/* perform minimal error analysis */
 	if (qc->flags & ATA_QCFLAG_FAILED) {
-- 
2.14.4