[SCSI] megaraid_sas: fix memory leak if SGL has zero length entries

commit 98cb7e44 ([SCSI] megaraid_sas: Sanity check user
supplied length before passing it to dma_alloc_coherent())
introduced a memory leak.  Memory allocated for entries
following zero length SGL entries will not be freed.

Reference: http://bugs.debian.org/688198Signed-off-by: Bjørn Mork <bjorn@mork.no>
Cc: <stable@vger.kernel.org>
Acked-by: Adam Radford <aradford@gmail.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/megaraid/megaraid_sas_base.c

@@ -4958,10 +4958,12 @@ megasas_mgmt_fw_ioctl(struct megasas_instance *instance,
 				    sense, sense_handle);
 	}
 
-	for (i = 0; i < ioc->sge_count && kbuff_arr[i]; i++) {
-		dma_free_coherent(&instance->pdev->dev,
-				    kern_sge32[i].length,
-				    kbuff_arr[i], kern_sge32[i].phys_addr);
+	for (i = 0; i < ioc->sge_count; i++) {
+		if (kbuff_arr[i])
+			dma_free_coherent(&instance->pdev->dev,
+					  kern_sge32[i].length,
+					  kbuff_arr[i],
+					  kern_sge32[i].phys_addr);
 	}
 
 	megasas_return_cmd(instance, cmd);