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authorKieran Bingham <kieran.bingham@ideasonboard.com>2023-07-05 00:22:48 +0100
committerKieran Bingham <kieran.bingham@ideasonboard.com>2023-07-11 15:19:13 +0100
commitf7a9f141569115a3da9edb758e3a5adbe723c330 (patch)
tree30349896cf96c25a08880c208626c2a7f1d9d057
parent22cc8bc25dae4b1457c852a7fb633526672d7032 (diff)
v4l2: v4l2_camera_proxy: Prevent ioctl sign-extensions
Handling ioctl's within applications is often wrapped with a helper such as xioctl. Unfortunately, there are many instances of xioctl which incorrectly handle the correct size of the ioctl request. This leads to incorrect sign-extension of ioctl's which have bit-31 set, and can cause values to be passed into the libcamera's v4l2 adaptation layer which no longer represent the true IOCTL code. Match the implementation of the Linux kernel and ensure that only 32 bits of the ioctl request are used by assigning to an unsigned int. Link: https://github.com/Motion-Project/motion/discussions/1636 Reviewed-by: Jacopo Mondi <jacopo.mondi@ideasonboard.com> Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
-rw-r--r--src/v4l2/v4l2_camera_proxy.cpp12
1 files changed, 11 insertions, 1 deletions
diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
index 55ff62cd..341f7902 100644
--- a/src/v4l2/v4l2_camera_proxy.cpp
+++ b/src/v4l2/v4l2_camera_proxy.cpp
@@ -778,10 +778,20 @@ const std::set<unsigned long> V4L2CameraProxy::supportedIoctls_ = {
VIDIOC_STREAMOFF,
};
-int V4L2CameraProxy::ioctl(V4L2CameraFile *file, unsigned long request, void *arg)
+int V4L2CameraProxy::ioctl(V4L2CameraFile *file, unsigned long longRequest, void *arg)
{
MutexLocker locker(proxyMutex_);
+ /*
+ * The Linux Kernel only processes 32 bits of an IOCTL.
+ *
+ * Prevent unexpected sign-extensions that could occur if applications
+ * use a signed int for the ioctl request, which would sign-extend to
+ * an incorrect value for unsigned longs on 64 bit architectures by
+ * explicitly casting as an unsigned int here.
+ */
+ unsigned int request = longRequest;
+
if (!arg && (_IOC_DIR(request) & _IOC_WRITE)) {
errno = EFAULT;
return -1;