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Subject[PATCH v4 03/15] scsi: ufs: verify command tag validity
Date
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@codeaurora.org>
Signed-off-by: Yaniv Gardi <ygardi@codeaurora.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
--
QUALCOMM ISRAEL, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation


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