Fnic: Fnic Driver crashed with NULL pointer reference

When issuing I/O request, if the I/O completes before returning from
fnic_queuecommand(), we may be referencing scsi_cmnd structure that may
be freed by interrupt handler. Acquring IO lock would synchronize
fnic_queuecommand and interrupt handler.

- Increment fnic version from 1.6.0.15 to 1.6.0.16

Signed-off-by: Hiral Shah <hishah@cisco.com>
Signed-off-by: Sesidhar Baddela <sebaddel@cisco.com>
Signed-off-by: Anil Chintalapati <achintal@cisco.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>

2 files changed, 19 insertions, 4 deletions

diff --git a/drivers/scsi/fnic/fnic.h b/drivers/scsi/fnic/fnic.h
index 977960b03c9f..3b73b96619e2 100644
--- a/drivers/scsi/fnic/fnic.h
+++ b/drivers/scsi/fnic/fnic.h
@@ -39,7 +39,7 @@
 
 #define DRV_NAME                "fnic"
 #define DRV_DESCRIPTION         "Cisco FCoE HBA Driver"
-#define DRV_VERSION             "1.6.0.15"
+#define DRV_VERSION             "1.6.0.16"
 #define PFX                     DRV_NAME ": "
 #define DFX                     DRV_NAME "%d: "
 
diff --git a/drivers/scsi/fnic/fnic_scsi.c b/drivers/scsi/fnic/fnic_scsi.c
index 29d23a3c0686..2097de42a147 100644
--- a/drivers/scsi/fnic/fnic_scsi.c
+++ b/drivers/scsi/fnic/fnic_scsi.c
@@ -421,9 +421,10 @@ static int fnic_queuecommand_lck(struct scsi_cmnd *sc, void (*done)(struct scsi_
         int ret;
         u64 cmd_trace;
         int sg_count = 0;
-        unsigned long flags;
+        unsigned long flags = 0;
         unsigned long ptr;
         struct fc_rport_priv *rdata;
+        spinlock_t *io_lock = NULL;
 
         if (unlikely(fnic_chk_state_flags_locked(fnic, FNIC_FLAGS_IO_BLOCKED)))
                 return SCSI_MLQUEUE_HOST_BUSY;
@@ -509,6 +510,13 @@ static int fnic_queuecommand_lck(struct scsi_cmnd *sc, void (*done)(struct scsi_
                 }
         }
 
+        /*
+        * Will acquire lock defore setting to IO initialized.
+        */
+
+        io_lock = fnic_io_lock_hash(fnic, sc);
+        spin_lock_irqsave(io_lock, flags);
+
         /* initialize rest of io_req */
         io_req->port_id = rport->port_id;
         io_req->start_time = jiffies;
@@ -525,11 +533,9 @@ static int fnic_queuecommand_lck(struct scsi_cmnd *sc, void (*done)(struct scsi_
                  * In case another thread cancelled the request,
                  * refetch the pointer under the lock.
                  */
-                spinlock_t *io_lock = fnic_io_lock_hash(fnic, sc);
                 FNIC_TRACE(fnic_queuecommand, sc->device->host->host_no,
                           sc->request->tag, sc, 0, 0, 0,
                           (((u64)CMD_FLAGS(sc) << 32) | CMD_STATE(sc)));
-                spin_lock_irqsave(io_lock, flags);
                 io_req = (struct fnic_io_req *)CMD_SP(sc);
                 CMD_SP(sc) = NULL;
                 CMD_STATE(sc) = FNIC_IOREQ_CMD_COMPLETE;
@@ -538,6 +544,10 @@ static int fnic_queuecommand_lck(struct scsi_cmnd *sc, void (*done)(struct scsi_
                         fnic_release_ioreq_buf(fnic, io_req, sc);
                         mempool_free(io_req, fnic->io_req_pool);
                 }
+                atomic_dec(&fnic->in_flight);
+                /* acquire host lock before returning to SCSI */
+                spin_lock(lp->host->host_lock);
+                return ret;
         } else {
                 atomic64_inc(&fnic_stats->io_stats.active_ios);
                 atomic64_inc(&fnic_stats->io_stats.num_ios);
@@ -559,6 +569,11 @@ out:
                   sc->request->tag, sc, io_req,
                   sg_count, cmd_trace,
                   (((u64)CMD_FLAGS(sc) >> 32) | CMD_STATE(sc)));
+
+        /* if only we issued IO, will we have the io lock */
+        if (CMD_FLAGS(sc) & FNIC_IO_INITIALIZED)
+                spin_unlock_irqrestore(io_lock, flags);
+
         atomic_dec(&fnic->in_flight);
         /* acquire host lock before returning to SCSI */
         spin_lock(lp->host->host_lock);