[030/264] [SCSI] megaraid_sas: Fix instance access in megasas_reset_timer

[Greg KH]

3.1-stable review patch.  If anyone has any objections, please let me know.

------------------

From: adam radford <aradford@xxxxxxxxx>

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@xxxxxxxxx>
Signed-off-by: James Bottomley <JBottomley@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>

---
 drivers/scsi/megaraid/megaraid_sas_base.c |    3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/drivers/scsi/megaraid/megaraid_sas_base.c
+++ b/drivers/scsi/megaraid/megaraid_sas_base.c
@@ -1907,7 +1907,6 @@ static int megasas_generic_reset(struct
 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;
 
@@ -1916,7 +1915,7 @@ blk_eh_timer_return megasas_reset_timer(
 		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);


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