This is a note to let you know that I've just added the patch titled
vfio/mdev: Do not allow a mdev_type to have a NULL parent pointer
to the 5.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
vfio-mdev-do-not-allow-a-mdev_type-to-have-a-null-pa.patch
and it can be found in the queue-5.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 915190a02a917a350ed34cbd1a4abedf935076d0
Author: Jason Gunthorpe <jgg@xxxxxxxxxx>
Date: Tue Apr 6 16:40:25 2021 -0300
vfio/mdev: Do not allow a mdev_type to have a NULL parent pointer
[ Upstream commit b5a1f8921d5040bb788492bf33a66758021e4be5 ]
There is a small race where the parent is NULL even though the kobj has
already been made visible in sysfs.
For instance the attribute_group is made visible in sysfs_create_files()
and the mdev_type_attr_show() does:
ret = attr->show(kobj, type->parent->dev, buf);
Which will crash on NULL parent. Move the parent setup to before the type
pointer leaves the stack frame.
Fixes: 7b96953bc640 ("vfio: Mediated device Core driver")
Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Reviewed-by: Max Gurtovoy <mgurtovoy@xxxxxxxxxx>
Reviewed-by: Cornelia Huck <cohuck@xxxxxxxxxx>
Signed-off-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Message-Id: <2-v2-d36939638fc6+d54-vfio2_jgg@xxxxxxxxxx>
Signed-off-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/vfio/mdev/mdev_sysfs.c b/drivers/vfio/mdev/mdev_sysfs.c
index 917fd84c1c6f..367ff5412a38 100644
--- a/drivers/vfio/mdev/mdev_sysfs.c
+++ b/drivers/vfio/mdev/mdev_sysfs.c
@@ -105,6 +105,7 @@ static struct mdev_type *add_mdev_supported_type(struct mdev_parent *parent,
return ERR_PTR(-ENOMEM);
type->kobj.kset = parent->mdev_types_kset;
+ type->parent = parent;
ret = kobject_init_and_add(&type->kobj, &mdev_type_ktype, NULL,
"%s-%s", dev_driver_string(parent->dev),
@@ -132,7 +133,6 @@ static struct mdev_type *add_mdev_supported_type(struct mdev_parent *parent,
}
type->group = group;
- type->parent = parent;
return type;
attrs_failed:
