syzbot is hitting use-after-free bug in uinput module [1]. This is because
kobject_uevent(KOBJ_REMOVE) is called again due to commit 0f4dafc0563c6c49
("Kobject: auto-cleanup on final unref") after memory allocation fault
injection made kobject_uevent(KOBJ_REMOVE) from device_del() from
input_unregister_device() fail, while uinput_destroy_device() is expecting
that kobject_uevent(KOBJ_REMOVE) is not called after device_del() from
input_unregister_device() completed.
Fix this problem by pretending as if kobject_uevent(KOBJ_REMOVE) from
device_del() from input_unregister_device() did not fail.
[1] https://syzkaller.appspot.com/bug?id=8b17c134fe938bbddd75a45afaa9e68af43a362d
Reported-by: syzbot <syzbot+f648cfb7e0b52bf7ae32@xxxxxxxxxxxxxxxxxxxxxxxxx>
Analyzed-by: Dmitry Torokhov <dmitry.torokhov@xxxxxxxxx>
Cc: Kay Sievers <kay@xxxxxxxx>
Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
---
drivers/input/input.c | 13 +++++++++++++
1 file changed, 13 insertions(+)
diff --git a/drivers/input/input.c b/drivers/input/input.c
index 3304aaaffe87..6df3c33ef3aa 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -2032,6 +2032,19 @@ static void __input_unregister_device(struct input_dev *dev)
mutex_unlock(&input_mutex);
device_del(&dev->dev);
+ /*
+ * Regarding input subsystem, we always take care of sending uevent at
+ * "unregister" time, and we do not expect to have uevent sent out at
+ * the final "put" time. Therefore, if we failed to send uevent at
+ * "unregister" time (due to e.g. fault injection), complain it and
+ * do not allow the final "put" time to send the remove uevent again.
+ */
+ if (dev->dev.kobj.state_add_uevent_sent &&
+ !dev->dev.kobj.state_remove_uevent_sent) {
+ dev->dev.kobj.state_remove_uevent_sent = 1;
+ pr_warn("Failed to send remove uevent for %s\n",
+ dev_name(&dev->dev));
+ }
}
static void devm_input_device_unregister(struct device *dev, void *res)
--
2.17.1
