[PATCH 1/1] cdev: cdev_put oops

[brking]

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@xxxxxxxxxx>
---

 linux-2.6-bjking1/fs/char_dev.c |    5 ++++-
 1 files changed, 4 insertions(+), 1 deletion(-)

diff -puN fs/char_dev.c~cdev_put_oops fs/char_dev.c
--- linux-2.6/fs/char_dev.c~cdev_put_oops	2005-07-07 08:20:09.000000000 -0500
+++ linux-2.6-bjking1/fs/char_dev.c	2005-07-07 08:20:09.000000000 -0500
@@ -276,9 +276,12 @@ static struct kobject *cdev_get(struct c
 
 void cdev_put(struct cdev *p)
 {
+	struct module *owner;
+
 	if (p) {
+		owner = p->owner;
 		kobject_put(&p->kobj);
-		module_put(p->owner);
+		module_put(owner);
 	}
 }
 
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