On Wed, 2019-06-19 at 09:05 +0200, Jan Kara wrote:

Once we unlock adapter->hw_lock in pvscsi_queue_lck() nothing prevents just queued scsi_cmnd from completing and freeing the request. Thus cmd->cmnd[0] dereference can dereference already freed request leading to kernel crashes or other issues (which one of our customers observed). Store cmd->cmnd[0] in a local variable before unlocking adapter->hw_lock to fix the issue.

CC: stable@vger.kernel.org Signed-off-by: Jan Kara jack@suse.cz

---

drivers/scsi/vmw_pvscsi.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/scsi/vmw_pvscsi.c b/drivers/scsi/vmw_pvscsi.c index ecee4b3ff073..377b07b2feeb 100644 --- a/drivers/scsi/vmw_pvscsi.c +++ b/drivers/scsi/vmw_pvscsi.c @@ -763,6 +763,7 @@ static int pvscsi_queue_lck(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd struct pvscsi_adapter *adapter = shost_priv(host); struct pvscsi_ctx *ctx; unsigned long flags;

• unsigned char op;

spin_lock_irqsave(&adapter->hw_lock, flags); @@ -775,13 +776,14 @@ static int pvscsi_queue_lck(struct scsi_cmnd *cmd, void (*done)(struct scsi_cmnd } cmd->scsi_done = done;

• op = cmd->cmnd[0];

dev_dbg(&cmd->device->sdev_gendev,

• "queued cmd %p, ctx %p, op=%x\n", cmd, ctx, cmd->cmnd[0]);
  

• "queued cmd %p, ctx %p, op=%x\n", cmd, ctx, op);
  

spin_unlock_irqrestore(&adapter->hw_lock, flags);

• pvscsi_kick_io(adapter, cmd->cmnd[0]);

• pvscsi_kick_io(adapter, op);

return 0; }

Reviewed-by: Ewan D. Milne emilne@redhat.com