scsi: ufs: Fix the SCSI abort handler

Make the following changes in ufshcd_abort():

 - Return FAILED instead of SUCCESS if the abort handler notices that a
   SCSI command has already been completed. Returning SUCCESS in this case
   triggers a use-after-free and may trigger a kernel crash.

 - Fix the code for aborting SCSI commands submitted to a WLUN.

The current approach for aborting SCSI commands that have been submitted to
a WLUN and that timed out is as follows:

 - Report to the SCSI core that the command has completed successfully.
   Let the block layer free any data buffers associated with the command.

 - Mark the command as outstanding in 'outstanding_reqs'.

 - If the block layer tries to reuse the tag associated with the aborted
   command, busy-wait until the tag is freed.

This approach can result in:

 - Memory corruption if the controller accesses the data buffer after the
   block layer has freed the associated data buffers.

 - A race condition if ufshcd_queuecommand() or ufshcd_exec_dev_cmd()
   checks the bit that corresponds to an aborted command in
   'outstanding_reqs' after it has been cleared and before it is reset.

 - High energy consumption if ufshcd_queuecommand() repeatedly returns
   SCSI_MLQUEUE_HOST_BUSY.

Fix this by reporting to the SCSI error handler that aborting a SCSI
command failed if the SCSI command was submitted to a WLUN.

Link: https://lore.kernel.org/r/20210722033439.26550-15-bvanassche@acm.org
Fixes: 7a7e66c65d41 ("scsi: ufs: Fix a race condition between ufshcd_abort() and eh_work()")
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Stanley Chu <stanley.chu@mediatek.com>
Cc: Can Guo <cang@codeaurora.org>
Cc: Asutosh Das <asutoshd@codeaurora.org>
Cc: Avri Altman <avri.altman@wdc.com>
Reviewed-by: Bean Huo <beanhuo@micron.com>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/ufs/ufshcd.c b/drivers/scsi/ufs/ufshcd.c
index e402cc9..d52ba03 100644 (file)
--- a/drivers/scsi/ufs/ufshcd.c
+++ b/drivers/scsi/ufs/ufshcd.c
@@ -2725,15 +2725,6 @@ static int ufshcd_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *cmd)
        WARN_ON(ufshcd_is_clkgating_allowed(hba) &&
                (hba->clk_gating.state != CLKS_ON));
 
-       if (unlikely(test_bit(tag, &hba->outstanding_reqs))) {
-               if (hba->pm_op_in_progress)
-                       set_host_byte(cmd, DID_BAD_TARGET);
-               else
-                       err = SCSI_MLQUEUE_HOST_BUSY;
-               ufshcd_release(hba);
-               goto out;
-       }
-
        lrbp = &hba->lrb[tag];
        WARN_ON(lrbp->cmd);
        lrbp->cmd = cmd;
@@ -2937,11 +2928,6 @@ static int ufshcd_exec_dev_cmd(struct ufs_hba *hba,
        req->timeout = msecs_to_jiffies(2 * timeout);
        blk_mq_start_request(req);
 
-       if (unlikely(test_bit(tag, &hba->outstanding_reqs))) {
-               err = -EBUSY;
-               goto out;
-       }
-
        lrbp = &hba->lrb[tag];
        WARN_ON(lrbp->cmd);
        err = ufshcd_compose_dev_cmd(hba, lrbp, cmd_type, tag);
@@ -6958,19 +6944,19 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
        unsigned int tag = cmd->request->tag;
        struct ufshcd_lrb *lrbp = &hba->lrb[tag];
        unsigned long flags;
-       int err = 0;
+       int err = FAILED;
        u32 reg;
 
        WARN_ONCE(tag < 0, "Invalid tag %d\n", tag);
 
        ufshcd_hold(hba, false);
        reg = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);
-       /* If command is already aborted/completed, return SUCCESS */
+       /* If command is already aborted/completed, return FAILED. */
        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;
+               goto release;
        }
 
        /* Print Transfer Request of aborted task */
@@ -6999,7 +6985,8 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
                dev_err(hba->dev,
                "%s: cmd was completed, but without a notifying intr, tag = %d",
                __func__, tag);
-               goto cleanup;
+               __ufshcd_transfer_req_compl(hba, 1UL << tag);
+               goto release;
        }
 
        /*
@@ -7012,36 +6999,33 @@ static int ufshcd_abort(struct scsi_cmnd *cmd)
         */
        if (lrbp->lun == UFS_UPIU_UFS_DEVICE_WLUN) {
                ufshcd_update_evt_hist(hba, UFS_EVT_ABORT, lrbp->lun);
-               __ufshcd_transfer_req_compl(hba, (1UL << tag));
-               set_bit(tag, &hba->outstanding_reqs);
+
                spin_lock_irqsave(host->host_lock, flags);
                hba->force_reset = true;
                ufshcd_schedule_eh_work(hba);
                spin_unlock_irqrestore(host->host_lock, flags);
-               goto out;
+               goto release;
        }
 
        /* Skip task abort in case previous aborts failed and report failure */
-       if (lrbp->req_abort_skip)
-               err = -EIO;
-       else
-               err = ufshcd_try_to_abort_task(hba, tag);
+       if (lrbp->req_abort_skip) {
+               dev_err(hba->dev, "%s: skipping abort\n", __func__);
+               ufshcd_set_req_abort_skip(hba, hba->outstanding_reqs);
+               goto release;
+       }
 
-       if (!err) {
-cleanup:
-               __ufshcd_transfer_req_compl(hba, (1UL << tag));
-out:
-               err = SUCCESS;
-       } else {
+       err = ufshcd_try_to_abort_task(hba, tag);
+       if (err) {
                dev_err(hba->dev, "%s: failed with err %d\n", __func__, err);
                ufshcd_set_req_abort_skip(hba, hba->outstanding_reqs);
                err = FAILED;
+               goto release;
        }
 
-       /*
-        * This ufshcd_release() corresponds to the original scsi cmd that got
-        * aborted here (as we won't get any IRQ for it).
-        */
+       err = SUCCESS;
+
+release:
+       /* Matches the ufshcd_hold() call at the start of this function. */
        ufshcd_release(hba);
        return err;
 }