[PATCH] cdev: cdev_put oops

While fixing an oops in the st driver in a dirty release path, I encountered an oops in cdev_put for cdevs allocated using cdev_alloc. If cdev_del is called when the cdev kobject still has an open user, when the last cdev_put is called, the cdev_put will call kobject_put, which will end up ultimately releasing the cdev in cdev_dynamic_release. Patch fixes the oops by preventing cdev_put from accessing freed memory. Signed-off-by: Brian King <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
mna · Jul 12, 2005 · 7da6844 · 7da6844
1 parent 50a5223
commit 7da6844
Showing 1 changed file with 2 additions and 1 deletion.
diff --git a/fs/char_dev.c b/fs/char_dev.c
@@ -277,8 +277,9 @@ static struct kobject *cdev_get(struct cdev *p)
 void cdev_put(struct cdev *p)
 {
 	if (p) {
+		struct module *owner = p->owner;
 		kobject_put(&p->kobj);
-		module_put(p->owner);
+		module_put(owner);
 	}
 }