| Message ID | 20200624145256.48266-18-paul.elder@ideasonboard.com |
|---|---|
| State | Accepted |
| Headers | show |
| Series |
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| Related | show |
diff --git a/src/v4l2/v4l2_camera.cpp b/src/v4l2/v4l2_camera.cpp index f7df9b8..ffc1230 100644 --- a/src/v4l2/v4l2_camera.cpp +++ b/src/v4l2/v4l2_camera.cpp @@ -147,6 +147,8 @@ int V4L2Camera::allocBuffers(unsigned int count) void V4L2Camera::freeBuffers() { + pendingRequests_.clear(); + Stream *stream = *camera_->streams().begin(); bufferAllocator_->free(stream); } @@ -188,10 +190,11 @@ int V4L2Camera::streamOn() int V4L2Camera::streamOff() { - /* \todo Restore buffers to reqbufs state? */ if (!isRunning_) return 0; + pendingRequests_.clear(); + int ret = camera_->stop(); if (ret < 0) return ret == -EACCES ? -EBUSY : ret;
V4L2 allows buffer queueing before streamon while libcamera does not. The compatibility layer thus saves these buffers in a pending queue until streamon, and then automatically queues them. However, this pending queue is not cleared when the buffers are freed, so the following sequence of actions will cause a use-after-free: 1. queue buffers 2. free buffers - buffers from 1. stay in pending queue but have been freed 3. queue buffers 4. streamon - buffers from 1. are enqueued, then the buffers from 3. are enqueued. Use-after-free segfault when libcamera tries to handle the enqueued buffers from 1. Fix this by clearing the pending request queue upon buffers being freed. Also clear the pending request queue on streamOff, for correctness. Signed-off-by: Paul Elder <paul.elder@ideasonboard.com> Reviewed-by: Jacopo Mondi <jacopo@jmondi.org> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com> --- No change in v4 Changes in v3: - reorder clearing the pending request queue, to before freeing buffers, and to after checking isRunning Changes in v2: - also clear pending request queue on streamOff - clarify the issue in changelog --- src/v4l2/v4l2_camera.cpp | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)