[PATCH AUTOSEL 4.19 15/16] driver core: bus: Return -EIO instead of 0 when show/store invalid bus attribute

[Sasha Levin <sashal@kernel.org>]

From: Zijun Hu <quic_zijuhu@quicinc.com>

[ Upstream commit c0fd973c108cdc22a384854bc4b3e288a9717bb2 ]

Return -EIO instead of 0 for below erroneous bus attribute operations:
 - read a bus attribute without show().
 - write a bus attribute without store().

Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/20240724-bus_fix-v2-1-5adbafc698fb@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/base/bus.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index e06a57936cc96..aad13af4175b8 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -103,7 +103,8 @@ static ssize_t bus_attr_show(struct kobject *kobj, struct attribute *attr,
 {
 	struct bus_attribute *bus_attr = to_bus_attr(attr);
 	struct subsys_private *subsys_priv = to_subsys_private(kobj);
-	ssize_t ret = 0;
+	/* return -EIO for reading a bus attribute without show() */
+	ssize_t ret = -EIO;
 
 	if (bus_attr->show)
 		ret = bus_attr->show(subsys_priv->bus, buf);
@@ -115,7 +116,8 @@ static ssize_t bus_attr_store(struct kobject *kobj, struct attribute *attr,
 {
 	struct bus_attribute *bus_attr = to_bus_attr(attr);
 	struct subsys_private *subsys_priv = to_subsys_private(kobj);
-	ssize_t ret = 0;
+	/* return -EIO for writing a bus attribute without store() */
+	ssize_t ret = -EIO;
 
 	if (bus_attr->store)
 		ret = bus_attr->store(subsys_priv->bus, buf, count);
-- 
2.43.0