[PATCH 4.19 16/32] media: radio-raremono: change devm_k*alloc to k*alloc

Greg Kroah-Hartman
2019-08-02T09:55:50Z

From: Luke Nowakowski-Krijger <lnowakow@eng.ucsd.edu>

commit c666355e60ddb4748ead3bdd983e3f7f2224aaf0 upstream.

Change devm_k*alloc to k*alloc to manually allocate memory

The manual allocation and freeing of memory is necessary because when
the USB radio is disconnected, the memory associated with devm_k*alloc
is freed. Meaning if we still have unresolved references to the radio
device, then we get use-after-free errors.

This patch fixes this by manually allocating memory, and freeing it in
the v4l2.release callback that gets called when the last radio device
exits.

Reported-and-tested-by: syzbot+a4387f5b6b799f6becbf@syzkaller.appspotmail.com

Signed-off-by: Luke Nowakowski-Krijger <lnowakow@eng.ucsd.edu>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
[hverkuil-cisco@xs4all.nl: cleaned up two small checkpatch.pl warnings]
[hverkuil-cisco@xs4all.nl: prefix subject with driver name]
Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/media/radio/radio-raremono.c | 30 +++++++++++++++++++++++-------
1 file changed, 23 insertions(+), 7 deletions(-)

--- a/drivers/media/radio/radio-raremono.c
+++ b/drivers/media/radio/radio-raremono.c
@@ -271,6 +271,14 @@ static int vidioc_g_frequency(struct fil
return 0;
}

+static void raremono_device_release(struct v4l2_device *v4l2_dev)
+{
+ struct raremono_device *radio = to_raremono_dev(v4l2_dev);
+
+ kfree(radio->buffer);
+ kfree(radio);
+}
+
/* File system interface */
static const struct v4l2_file_operations usb_raremono_fops = {
.owner = THIS_MODULE,
@@ -295,12 +303,14 @@ static int usb_raremono_probe(struct usb
struct raremono_device *radio;
int retval = 0;

- radio = devm_kzalloc(&intf->dev, sizeof(struct raremono_device), GFP_KERNEL);
- if (radio)
- radio->buffer = devm_kmalloc(&intf->dev, BUFFER_LENGTH, GFP_KERNEL);
-
- if (!radio || !radio->buffer)
+ radio = kzalloc(sizeof(*radio), GFP_KERNEL);
+ if (!radio)
+ return -ENOMEM;
+ radio->buffer = kmalloc(BUFFER_LENGTH, GFP_KERNEL);
+ if (!radio->buffer) {
+ kfree(radio);
return -ENOMEM;
+ }

radio->usbdev = interface_to_usbdev(intf);
radio->intf = intf;
@@ -324,7 +334,8 @@ static int usb_raremono_probe(struct usb
if (retval != 3 ||
(get_unaligned_be16(&radio->buffer[1]) & 0xfff) == 0x0242) {
dev_info(&intf->dev, "this is not Thanko's Raremono.\n");
- return -ENODEV;
+ retval = -ENODEV;
+ goto free_mem;
}

dev_info(&intf->dev, "Thanko's Raremono connected: (%04X:%04X)\n",
@@ -333,7 +344,7 @@ static int usb_raremono_probe(struct usb
retval = v4l2_device_register(&intf->dev, &radio->v4l2_dev);
if (retval < 0) {
dev_err(&intf->dev, "couldn't register v4l2_device\n");
- return retval;
+ goto free_mem;
}

mutex_init(&radio->lock);
@@ -345,6 +356,7 @@ static int usb_raremono_probe(struct usb
radio->vdev.ioctl_ops = &usb_raremono_ioctl_ops;
radio->vdev.lock = &radio->lock;
radio->vdev.release = video_device_release_empty;
+ radio->v4l2_dev.release = raremono_device_release;

usb_set_intfdata(intf, &radio->v4l2_dev);

@@ -360,6 +372,10 @@ static int usb_raremono_probe(struct usb
}
dev_err(&intf->dev, "could not register video device\n");
v4l2_device_unregister(&radio->v4l2_dev);
+
+free_mem:
+ kfree(radio->buffer);
+ kfree(radio);
return retval;
}