Patch "isa: Prevent NULL dereference in isa_bus driver callbacks" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

isa: Prevent NULL dereference in isa_bus driver callbacks

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
isa-prevent-null-dereference-in-isa_bus-driver-callbacks.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: William Breathitt Gray <[email protected]>
Date: Wed, 8 Nov 2017 10:23:11 -0500
Subject: isa: Prevent NULL dereference in isa_bus driver callbacks

From: William Breathitt Gray <[email protected]>

commit 5a244727f428a06634f22bb890e78024ab0c89f3 upstream.

The isa_driver structure for an isa_bus device is stored in the device platform_data member of the respective device structure. This platform_data member may be reset to NULL if isa_driver match callback for the device fails, indicating a device unsupported by the ISA driver.

This patch fixes a possible NULL pointer dereference if one of the isa_driver callbacks to attempted for an unsupported device. This error should not occur in practice since ISA devices are typically manually configured and loaded by the users, but we may as well prevent this error from popping up for the 0day testers.

---
 drivers/base/isa.c |   10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

@@ -39,7 +39,7 @@ static int isa_bus_probe(struct device *
 {
 	struct isa_driver *isa_driver = dev->platform_data;
 
-	if (isa_driver->probe)
+	if (isa_driver && isa_driver->probe)
 		return isa_driver->probe(dev, to_isa_dev(dev)->id);
 
 	return 0;

@@ -49,7 +49,7 @@ static int isa_bus_remove(struct device
 {
 	struct isa_driver *isa_driver = dev->platform_data;
 
-	if (isa_driver->remove)
+	if (isa_driver && isa_driver->remove)
 		return isa_driver->remove(dev, to_isa_dev(dev)->id);
 
 	return 0;

@@ -59,7 +59,7 @@ static void isa_bus_shutdown(struct devi
 {
 	struct isa_driver *isa_driver = dev->platform_data;
 
-	if (isa_driver->shutdown)
+	if (isa_driver && isa_driver->shutdown)
 		isa_driver->shutdown(dev, to_isa_dev(dev)->id);
 }
 

@@ -67,7 +67,7 @@ static int isa_bus_suspend(struct device
 {
 	struct isa_driver *isa_driver = dev->platform_data;
 
-	if (isa_driver->suspend)
+	if (isa_driver && isa_driver->suspend)
 		return isa_driver->suspend(dev, to_isa_dev(dev)->id, state);
 
 	return 0;

@@ -77,7 +77,7 @@ static int isa_bus_resume(struct device
 {
 	struct isa_driver *isa_driver = dev->platform_data;
 
-	if (isa_driver->resume)
+	if (isa_driver && isa_driver->resume)
 		return isa_driver->resume(dev, to_isa_dev(dev)->id);
 
 	return 0;

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/isa-prevent-null-dereference-in-isa_bus-driver-callbacks.patch