[PATCH 12/29] drivers, media: convert s2255_dev.num_channels from atomic_t to refcount_t
From: Elena Reshetova <elena.reshetova@intel.com>
Date: 2017-03-06 14:28:00
Also in:
linux-bcache, linux-media, linux-pci, linux-raid, linux-s390, linux-scsi, linux-serial, lkml
Subsystem:
media input infrastructure (v4l/dvb), the rest · Maintainers:
Mauro Carvalho Chehab, Linus Torvalds
refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> Signed-off-by: Hans Liljestrand <redacted> Signed-off-by: Kees Cook <redacted> Signed-off-by: David Windsor <redacted> --- drivers/media/usb/s2255/s2255drv.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/drivers/media/usb/s2255/s2255drv.c b/drivers/media/usb/s2255/s2255drv.c
index a9d4484..2b4b009 100644
--- a/drivers/media/usb/s2255/s2255drv.c
+++ b/drivers/media/usb/s2255/s2255drv.c@@ -36,6 +36,7 @@ #include <linux/firmware.h> #include <linux/kernel.h> #include <linux/mutex.h> +#include <linux/refcount.h> #include <linux/slab.h> #include <linux/videodev2.h> #include <linux/mm.h>
@@ -256,7 +257,7 @@ struct s2255_vc { struct s2255_dev { struct s2255_vc vc[MAX_CHANNELS]; struct v4l2_device v4l2_dev; - atomic_t num_channels; + refcount_t num_channels; int frames; struct mutex lock; /* channels[].vdev.lock */ struct mutex cmdlock; /* protects cmdbuf */
@@ -1581,11 +1582,11 @@ static void s2255_video_device_release(struct video_device *vdev) container_of(vdev, struct s2255_vc, vdev); dprintk(dev, 4, "%s, chnls: %d\n", __func__, - atomic_read(&dev->num_channels)); + refcount_read(&dev->num_channels)); v4l2_ctrl_handler_free(&vc->hdl); - if (atomic_dec_and_test(&dev->num_channels)) + if (refcount_dec_and_test(&dev->num_channels)) s2255_destroy(dev); return; }
@@ -1688,7 +1689,7 @@ static int s2255_probe_v4l(struct s2255_dev *dev) "failed to register video device!\n"); break; } - atomic_inc(&dev->num_channels); + refcount_set(&dev->num_channels, 1); v4l2_info(&dev->v4l2_dev, "V4L2 device registered as %s\n", video_device_node_name(&vc->vdev));
@@ -1696,11 +1697,11 @@ static int s2255_probe_v4l(struct s2255_dev *dev) pr_info("Sensoray 2255 V4L driver Revision: %s\n", S2255_VERSION); /* if no channels registered, return error and probe will fail*/ - if (atomic_read(&dev->num_channels) == 0) { + if (refcount_read(&dev->num_channels) == 0) { v4l2_device_unregister(&dev->v4l2_dev); return ret; } - if (atomic_read(&dev->num_channels) != MAX_CHANNELS) + if (refcount_read(&dev->num_channels) != MAX_CHANNELS) pr_warn("s2255: Not all channels available.\n"); return 0; }
@@ -2248,7 +2249,7 @@ static int s2255_probe(struct usb_interface *interface, goto errorFWDATA1; } - atomic_set(&dev->num_channels, 0); + refcount_set(&dev->num_channels, 0); dev->pid = id->idProduct; dev->fw_data = kzalloc(sizeof(struct s2255_fw), GFP_KERNEL); if (!dev->fw_data)
@@ -2368,12 +2369,12 @@ static void s2255_disconnect(struct usb_interface *interface) { struct s2255_dev *dev = to_s2255_dev(usb_get_intfdata(interface)); int i; - int channels = atomic_read(&dev->num_channels); + int channels = refcount_read(&dev->num_channels); mutex_lock(&dev->lock); v4l2_device_disconnect(&dev->v4l2_dev); mutex_unlock(&dev->lock); /*see comments in the uvc_driver.c usb disconnect function */ - atomic_inc(&dev->num_channels); + refcount_inc(&dev->num_channels); /* unregister each video device. */ for (i = 0; i < channels; i++) video_unregister_device(&dev->vc[i].vdev);
@@ -2386,7 +2387,7 @@ static void s2255_disconnect(struct usb_interface *interface) dev->vc[i].vidstatus_ready = 1; wake_up(&dev->vc[i].wait_vidstatus); } - if (atomic_dec_and_test(&dev->num_channels)) + if (refcount_dec_and_test(&dev->num_channels)) s2255_destroy(dev); dev_info(&interface->dev, "%s\n", __func__); }
--
2.7.4