media: radio-raremono: change devm_k*alloc to k*alloc

BugLink: https://bugs.launchpad.net/bugs/1839213
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>
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

diff --git a/drivers/media/radio/radio-raremono.c b/drivers/media/radio/radio-raremono.c
index 70a2c86774ce5a345fc9a5f9a8bc2d2a5290593f..07ef858e505711abcb7214095b2f83ae5eff660b 100644 (file)
--- a/drivers/media/radio/radio-raremono.c
+++ b/drivers/media/radio/radio-raremono.c
@@ -283,6 +283,14 @@ static int vidioc_g_frequency(struct file *file, void *priv,
        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,
@@ -307,12 +315,14 @@ static int usb_raremono_probe(struct usb_interface *intf,
        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;
@@ -336,7 +346,8 @@ static int usb_raremono_probe(struct usb_interface *intf,
        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",
@@ -345,7 +356,7 @@ static int usb_raremono_probe(struct usb_interface *intf,
        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);
@@ -357,6 +368,7 @@ static int usb_raremono_probe(struct usb_interface *intf,
        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);
 
@@ -372,6 +384,10 @@ static int usb_raremono_probe(struct usb_interface *intf,
        }
        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;
 }