scsi: ses: Fix crash caused by kfree an invalid pointer

driver inclusion
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I3BNT6
CVE: NA

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

We can get a crash when disconnecting the iSCSI session,
the call trace like this:

  [ffff00002a00fb70] kfree at ffff00000830e224
  [ffff00002a00fba0] ses_intf_remove at ffff000001f200e4
  [ffff00002a00fbd0] device_del at ffff0000086b6a98
  [ffff00002a00fc50] device_unregister at ffff0000086b6d58
  [ffff00002a00fc70] __scsi_remove_device at ffff00000870608c
  [ffff00002a00fca0] scsi_remove_device at ffff000008706134
  [ffff00002a00fcc0] __scsi_remove_target at ffff0000087062e4
  [ffff00002a00fd10] scsi_remove_target at ffff0000087064c0
  [ffff00002a00fd70] __iscsi_unbind_session at ffff000001c872c4
  [ffff00002a00fdb0] process_one_work at ffff00000810f35c
  [ffff00002a00fe00] worker_thread at ffff00000810f648
  [ffff00002a00fe70] kthread at ffff000008116e98

In ses_intf_add, components count could be 0, and kcalloc 0 size scomp,
but not saved in edev->component[i].scratch

In this situation, edev->component[0].scratch is an invalid pointer,
when kfree it in ses_intf_remove_enclosure, a crash like above would happen
The call trace also could be other random cases when kfree cannot catch
the invalid pointer

We should not use edev->component[] array when the components count is 0
We also need check index when use edev->component[] array in
ses_enclosure_data_process

Another fix option is report error and do not attach in ses_intf_add if we
meet a zero component enclosure
Tested-by: NZeng Zhicong <timmyzeng@163.com>
Signed-off-by: NDing Hui <dinghui@sangfor.com.cn>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>
Signed-off-by: NCheng Jian <cj.chengjian@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>
Reviewed-by: NJason Yan <yanaijie@huawei.com>
Acked-by: NXie XiuQi <xiexiuqi@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/scsi/ses.c

@@ -491,9 +491,6 @@ static int ses_enclosure_find_by_addr(struct enclosure_device *edev,
 	int i;
 	struct ses_component *scomp;
 
-	if (!edev->component[0].scratch)
-		return 0;
-
 	for (i = 0; i < edev->components; i++) {
 		scomp = edev->component[i].scratch;
 		if (scomp->addr != efd->addr)
@@ -579,8 +576,10 @@ static void ses_enclosure_data_process(struct enclosure_device *edev,
 						components++,
 						type_ptr[0],
 						name);
-				else
+				else if (components < edev->components)
 					ecomp = &edev->component[components++];
+				else
+					ecomp = ERR_PTR(-EINVAL);
 
 				if (!IS_ERR(ecomp)) {
 					if (addl_desc_ptr)
@@ -745,9 +744,11 @@ static int ses_intf_add(struct device *cdev,
 		buf = NULL;
 	}
 page2_not_supported:
-	scomp = kcalloc(components, sizeof(struct ses_component), GFP_KERNEL);
-	if (!scomp)
-		goto err_free;
+	if (components > 0) {
+		scomp = kcalloc(components, sizeof(struct ses_component), GFP_KERNEL);
+		if (!scomp)
+			goto err_free;
+	}
 
 	edev = enclosure_register(cdev->parent, dev_name(&sdev->sdev_gendev),
 				  components, &ses_enclosure_callbacks);
@@ -827,7 +828,8 @@ static void ses_intf_remove_enclosure(struct scsi_device *sdev)
 	kfree(ses_dev->page2);
 	kfree(ses_dev);
 
-	kfree(edev->component[0].scratch);
+	if (edev->components > 0)
+		kfree(edev->component[0].scratch);
 
 	put_device(&edev->edev);
 	enclosure_unregister(edev);