Messages in this thread | | | Subject | Re: [PATCH] rapidio: Avoid data race between file operation callbacks and mport_cdev_add(). | From | "alex.b" <> | Date | Sun, 26 Apr 2020 11:19:51 -0400 |
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On 2020-04-26 7:29 a.m., madhuparnabhowmik10@gmail.com wrote: > From: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com> > > Fields of md(mport_dev) are set after cdev_device_add(). > However, the file operation callbacks can be called after > cdev_device_add() and therefore accesses to fields of md in the > callbacks can race with the rest of the mport_cdev_add() function. > > One such example is INIT_LIST_HEAD(&md->portwrites) in > mport_cdev_add(), the list is initialised after cdev_device_add(). > This can race with list_add_tail(&pw_filter->md_node,&md->portwrites) > in rio_mport_add_pw_filter() which is called by unlocked_ioctl. > > To avoid such data races use cdev_device_add() after initializing md. > > Found by Linux Driver Verification project (linuxtesting.org). > > Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com> > --- > drivers/rapidio/devices/rio_mport_cdev.c | 14 +++++++------- > 1 file changed, 7 insertions(+), 7 deletions(-) > > diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c > index 8155f59ece38..40296378e5ee 100644 > --- a/drivers/rapidio/devices/rio_mport_cdev.c > +++ b/drivers/rapidio/devices/rio_mport_cdev.c > @@ -2379,13 +2379,6 @@ static struct mport_dev *mport_cdev_add(struct rio_mport *mport) > cdev_init(&md->cdev, &mport_fops); > md->cdev.owner = THIS_MODULE; > > - ret = cdev_device_add(&md->cdev, &md->dev); > - if (ret) { > - rmcd_error("Failed to register mport %d (err=%d)", > - mport->id, ret); > - goto err_cdev; > - } > - > INIT_LIST_HEAD(&md->doorbells); > spin_lock_init(&md->db_lock); > INIT_LIST_HEAD(&md->portwrites); > @@ -2405,6 +2398,13 @@ static struct mport_dev *mport_cdev_add(struct rio_mport *mport) > #else > md->properties.transfer_mode |= RIO_TRANSFER_MODE_TRANSFER; > #endif > + > + ret = cdev_device_add(&md->cdev, &md->dev); > + if (ret) { > + rmcd_error("Failed to register mport %d (err=%d)", > + mport->id, ret); > + goto err_cdev; > + } > ret = rio_query_mport(mport, &attr); > if (!ret) { > md->properties.flags = attr.flags;
Acked-by: Alexandre Bounine <alex.bou9@gmail.com>
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