[Linux-kernel-mentees] [PATCH v2] Media: Radio: Change devm_k*alloc to k*alloc
From: Luke Nowakowski-Krijger <hidden>
Date: 2019-05-24 07:49:09
Subsystem:
media input infrastructure (v4l/dvb), thanko's raremono am/fm/sw radio receiver usb driver, the rest · Maintainers:
Mauro Carvalho Chehab, Hans Verkuil, Linus Torvalds
Changed devm_k*alloc to k*alloc to manually allocate memory. Memory is freed in vdev.release callback which is now in raremono_device_release. This patch aims to fix the use-after-free read described in https://syzkaller.appspot.com/bug?extid=a4387f5b6b799f6becbf Signed-off-by: Luke Nowakowski-Krijger <lnowakow at eng.ucsd.edu> --- drivers/media/radio/radio-raremono.c | 39 ++++++++++++++++++++++------ 1 file changed, 31 insertions(+), 8 deletions(-)
diff --git a/drivers/media/radio/radio-raremono.c b/drivers/media/radio/radio-raremono.c
index 5e782b3c2fa9..b3fb0893182d 100644
--- a/drivers/media/radio/radio-raremono.c
+++ b/drivers/media/radio/radio-raremono.c@@ -271,6 +271,18 @@ static int vidioc_g_frequency(struct file *file, void *priv, return 0; } +static void raremono_device_release(struct video_device *vdev) +{ + struct raremono_device *radio = + video_get_drvdata(vdev); + + if (radio) { + kfree(radio->buffer); + kfree(radio); + } +} + + /* File system interface */ static const struct v4l2_file_operations usb_raremono_fops = { .owner = THIS_MODULE,
@@ -295,12 +307,15 @@ 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(struct raremono_device), 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 +339,9 @@ 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",
@@ -333,7 +350,7 @@ 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);
@@ -344,7 +361,7 @@ static int usb_raremono_probe(struct usb_interface *intf, radio->vdev.fops = &usb_raremono_fops; radio->vdev.ioctl_ops = &usb_raremono_ioctl_ops; radio->vdev.lock = &radio->lock; - radio->vdev.release = video_device_release_empty; + radio->vdev.release = raremono_device_release; usb_set_intfdata(intf, &radio->v4l2_dev);
@@ -353,13 +370,19 @@ static int usb_raremono_probe(struct usb_interface *intf, raremono_cmd_main(radio, BAND_FM, 95160); retval = video_register_device(&radio->vdev, VFL_TYPE_RADIO, -1); + if (retval == 0) { dev_info(&intf->dev, "V4L2 device registered as %s\n", video_device_node_name(&radio->vdev)); return 0; } + 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; }
--
2.20.1