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[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 <brking@us.ibm.com> Cc: <viro@parcelfarce.linux.theplanet.co.uk> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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@ -277,8 +277,9 @@ static struct kobject *cdev_get(struct cdev *p)
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void cdev_put(struct cdev *p)
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{
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if (p) {
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struct module *owner = p->owner;
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kobject_put(&p->kobj);
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module_put(p->owner);
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module_put(owner);
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}
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}
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