s390/cio: check the subchannel validity for dev_busid

Check the validity of subchanel before reading other fields in the schib. Fixes: d3683c0 ("s390/cio: add dev_busid sysfs entry for each subchannel") CC: <[email protected]> Reported-by: Cornelia Huck <[email protected]> Signed-off-by: Vineeth Vijayan <[email protected]> Reviewed-by: Cornelia Huck <[email protected]> Link: https://lore.kernel.org/r/[email protected] Signed-off-by: Vasily Gorbik <[email protected]>
pop-os · Nov 8, 2021 · a4751f1 · a4751f1
1 parent 9d48c7a
commit a4751f1
Showing 1 changed file with 2 additions and 2 deletions.
diff --git a/drivers/s390/cio/css.c b/drivers/s390/cio/css.c
@@ -437,8 +437,8 @@ static ssize_t dev_busid_show(struct device *dev,
 	struct subchannel *sch = to_subchannel(dev);
 	struct pmcw *pmcw = &sch->schib.pmcw;
 
-	if ((pmcw->st == SUBCHANNEL_TYPE_IO ||
-	     pmcw->st == SUBCHANNEL_TYPE_MSG) && pmcw->dnv)
+	if ((pmcw->st == SUBCHANNEL_TYPE_IO && pmcw->dnv) ||
+	    (pmcw->st == SUBCHANNEL_TYPE_MSG && pmcw->w))
 		return sysfs_emit(buf, "0.%x.%04x\n", sch->schid.ssid,
 				  pmcw->dev);
 	else