megaraid_sas: Fix instance access in megasas_reset_timer

commit f575c5d3ebdca3b0482847d8fcba971767754a9e upstream.

The following patch for megaraid_sas will fix a potential bad pointer access
in megasas_reset_timer(), when a MegaRAID 9265/9285 or 9360/9380 gets a
timeout.  megasas_build_io_fusion() sets SCp.ptr to be a struct
megasas_cmd_fusion *, but then megasas_reset_timer() was casting SCp.ptr to be
a struct megasas_cmd *, then trying to access cmd->instance, which is invalid.

Just loading instance from scmd->device->host->hostdata in
megasas_reset_timer() fixes the issue.

Signed-off-by: Adam Radford <aradford@gmail.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1 insertions, 2 deletions

diff --git a/drivers/scsi/megaraid/megaraid_sas_base.c b/drivers/scsi/megaraid/megaraid_sas_base.c
index 2d8cdce7b2f..e6e30f4da1f 100644
--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -1906,7 +1906,6 @@ static int megasas_generic_reset(struct scsi_cmnd *scmd)
 static enum
 blk_eh_timer_return megasas_reset_timer(struct scsi_cmnd *scmd)
 {
-        struct megasas_cmd *cmd = (struct megasas_cmd *)scmd->SCp.ptr;
         struct megasas_instance *instance;
         unsigned long flags;
 
@@ -1915,7 +1914,7 @@ blk_eh_timer_return megasas_reset_timer(struct scsi_cmnd *scmd)
                 return BLK_EH_NOT_HANDLED;
         }
 
-        instance = cmd->instance;
+        instance = (struct megasas_instance *)scmd->device->host->hostdata;
         if (!(instance->flag & MEGASAS_FW_BUSY)) {
                 /* FW is busy, throttle IO */
                 spin_lock_irqsave(instance->host->host_lock, flags);