linux-kernel - [PATCH v5 03/15] scsi: ufs: verify command tag validity

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Date:	Tue, 27 Oct 2015 12:44:05 +0200
From:	Yaniv Gardi <ygardi@...eaurora.org>
To:	robherring2@...il.com, James.Bottomley@...senPartnership.com,
	pebolle@...cali.nl, hch@...radead.org
Cc:	linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
	linux-arm-msm@...r.kernel.org, santoshsy@...il.com,
	linux-scsi-owner@...r.kernel.org, subhashj@...eaurora.org,
	ygardi@...eaurora.org, gbroner@...eaurora.org,
	draviv@...eaurora.org, Vinayak Holikatti <vinholikatti@...il.com>,
	"James E.J. Bottomley" <JBottomley@...n.com>
Subject: [PATCH v5 03/15] scsi: ufs: verify command tag validity

A race condition appear to exist between request completion when
scsi_done() is called to end the request and set the tag back to
-1 (at blk_queue_end_tag() scsi_end_request), and scsi layer error
handling which aborts the command and reuses it to request sense
data. Sending the request sense is done with tag which was set to -1
and so it is invalid.
Assert command tag passed from scsi layer is valid.

Signed-off-by: Gilad Broner <gbroner@...eaurora.org>
Signed-off-by: Yaniv Gardi <ygardi@...eaurora.org>

---
 drivers/scsi/ufs/ufshcd.c | 24 ++++++++++++++++++++++--
 1 file changed, 22 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index 2d3ebca..8860a57 100644
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -190,6 +190,10 @@ static int ufshcd_config_pwr_mode(struct ufs_hba *hba,
 		struct ufs_pa_layer_attr *desired_pwr_mode);
 static int ufshcd_change_power_mode(struct ufs_hba *hba,
 			     struct ufs_pa_layer_attr *pwr_mode);
+static inline bool ufshcd_valid_tag(struct ufs_hba *hba, int tag)
+{
+	return tag >= 0 && tag < hba->nutrs;
+}
 
 static inline int ufshcd_enable_irq(struct ufs_hba *hba)
 {
@@ -1310,6 +1314,12 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
 	hba = shost_priv(host);
 
 	tag = cmd->request->tag;
+	if (!ufshcd_valid_tag(hba, tag)) {
+		dev_err(hba->dev,
+			"%s: invalid command tag %d: cmd=0x%p, cmd->request=0x%p",
+			__func__, tag, cmd, cmd->request);
+		BUG();
+	}
 
 	spin_lock_irqsave(hba->host->host_lock, flags);
 	switch (hba->ufshcd_state) {
@@ -3862,13 +3872,23 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
 	host = cmd->device->host;
 	hba = shost_priv(host);
 	tag = cmd->request->tag;
+	if (!ufshcd_valid_tag(hba, tag)) {
+		dev_err(hba->dev,
+			"%s: invalid command tag %d: cmd=0x%p, cmd->request=0x%p",
+			__func__, tag, cmd, cmd->request);
+		BUG();
+	}
 
 	ufshcd_hold(hba, false);
+	reg = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);
 	/* If command is already aborted/completed, return SUCCESS */
-	if (!(test_bit(tag, &hba->outstanding_reqs)))
+	if (!(test_bit(tag, &hba->outstanding_reqs))) {
+		dev_err(hba->dev,
+			"%s: cmd at tag %d already completed, outstanding=0x%lx, doorbell=0x%x\n",
+			__func__, tag, hba->outstanding_reqs, reg);
 		goto out;
+	}
 
-	reg = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);
 	if (!(reg & (1 << tag))) {
 		dev_err(hba->dev,
 		"%s: cmd was completed, but without a notifying intr, tag = %d",
-- 
1.8.5.2

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