This is a note to let you know that I've just added the patch titled
pps: Fix a use-after free bug when unregistering a source.
to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-next branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will also be merged in the next major kernel release
during the merge window.
If you have any questions about this process, please let me know.
>From d953e0e837e65ecc1ddaa4f9560f7925878a0de6 Mon Sep 17 00:00:00 2001
From: George Spelvin <[email protected]>
Date: Tue, 12 Feb 2013 02:27:20 -0500
Subject: pps: Fix a use-after free bug when unregistering a source.
Remove the cdev from the system (with cdev_del) *before* deallocating it
(in pps_device_destruct, called via kobject_put from device_destroy).
Also prevent deallocating a device with open file handles.
A better long-term fix is probably to remove the cdev from the pps_device
entirely, and instead have all devices reference one global cdev. Then
the deallocation ordering becomes simpler.
But that's more complex and invasive change, so we leave that
for later.
Signed-off-by: George Spelvin <[email protected]>
Cc: stable <[email protected]>
Acked-by: Rodolfo Giometti <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/pps/pps.c | 14 ++++++++++----
1 file changed, 10 insertions(+), 4 deletions(-)
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index a70e384..6437703 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -247,12 +247,15 @@ static int pps_cdev_open(struct inode *inode, struct file
*file)
struct pps_device *pps = container_of(inode->i_cdev,
struct pps_device, cdev);
file->private_data = pps;
-
+ kobject_get(&pps->dev->kobj);
return 0;
}
static int pps_cdev_release(struct inode *inode, struct file *file)
{
+ struct pps_device *pps = container_of(inode->i_cdev,
+ struct pps_device, cdev);
+ kobject_put(&pps->dev->kobj);
return 0;
}
@@ -274,8 +277,10 @@ static void pps_device_destruct(struct device *dev)
{
struct pps_device *pps = dev_get_drvdata(dev);
- /* release id here to protect others from using it while it's
- * still in use */
+ cdev_del(&pps->cdev);
+
+ /* Now we can release the ID for re-use */
+ pr_debug("deallocating pps%d\n", pps->id);
mutex_lock(&pps_idr_lock);
idr_remove(&pps_idr, pps->id);
mutex_unlock(&pps_idr_lock);
@@ -332,6 +337,7 @@ int pps_register_cdev(struct pps_device *pps)
goto del_cdev;
}
+ /* Override the release function with our own */
pps->dev->release = pps_device_destruct;
pr_debug("source %s got cdev (%d:%d)\n", pps->info.name,
@@ -352,9 +358,9 @@ free_idr:
void pps_unregister_cdev(struct pps_device *pps)
{
+ pr_debug("unregistering pps%d\n", pps->id);
pps->lookup_cookie = NULL;
device_destroy(pps_class, pps->dev->devt);
- cdev_del(&pps->cdev);
}
/*
--
1.8.1.rc1.5.g7e0651a
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