On Tue, Jan 25, 2022 at 01:19:30AM +0800, Zhou Qingyang wrote:
> In saa7134_initdev(), the return value of vdev_init() is assigned to
> dev->video_dev and there is a dereference of it after that. The return
> value of vdev_init() will be NULL on the failure allocation, which could
> lead to NULL pointer dereference.
>
> The same as dev->vbi_dev.
>
> Fix this bug by adding a NULL check of dev->video_dev and dev->vbi_dev.
>
> This bug was found by a static analyzer.
>
> Builds with 'make allyesconfig' show no new warnings,
> and our static analyzer no longer warns about this code.
>
> Fixes: a9622391acb ("V4L/DVB (6792): Fix VBI support")
> Signed-off-by: Zhou Qingyang <zhou1615@xxxxxxx>
> ---
> The analysis employs differential checking to identify inconsistent
> security operations (e.g., checks or kfrees) between two code paths
> and confirms that the inconsistent operations are not recovered in the
> current function or the callers, so they constitute bugs.
>
> Note that, as a bug found by static analysis, it can be a false
> positive or hard to trigger. Multiple researchers have cross-reviewed
> the bug.
>
> drivers/media/pci/saa7134/saa7134-core.c | 10 ++++++++++
> 1 file changed, 10 insertions(+)
>
> diff --git a/drivers/media/pci/saa7134/saa7134-core.c b/drivers/media/pci/saa7134/saa7134-core.c
> index 96328b0af164..0de0b00540b6 100644
> --- a/drivers/media/pci/saa7134/saa7134-core.c
> +++ b/drivers/media/pci/saa7134/saa7134-core.c
> @@ -1202,6 +1202,11 @@ static int saa7134_initdev(struct pci_dev *pci_dev,
> pr_info("%s: Overlay support disabled.\n", dev->name);
>
> dev->video_dev = vdev_init(dev,&saa7134_video_template,"video");
> + if (!dev->video_dev) {
> + err = -ENOMEM;
> + goto err_unregister_video;
> + }
> +
> dev->video_dev->ctrl_handler = &dev->ctrl_handler;
> dev->video_dev->lock = &dev->lock;
> dev->video_dev->queue = &dev->video_vbq;
> @@ -1224,6 +1229,11 @@ static int saa7134_initdev(struct pci_dev *pci_dev,
> dev->name, video_device_node_name(dev->video_dev));
>
> dev->vbi_dev = vdev_init(dev, &saa7134_video_template, "vbi");
> + if (!dev->vbi_dev) {
> + err = -ENOMEM;
> + goto err_unregister_video;
> + }
> +
> dev->vbi_dev->ctrl_handler = &dev->ctrl_handler;
> dev->vbi_dev->lock = &dev->lock;
> dev->vbi_dev->queue = &dev->vbi_vbq;
> --
> 2.25.1
>
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issue.
