NekoCWD/libcamera
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libcamera: gst: Fix double-free when acquire_buffer fails

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If gst_buffer_pool_acquire_buffer in gst_libcamera_task_run fails, the
unique_ptr to the request-object gets reset and hence, its destructor
is called. However, the wrap-object points to the same object and is
still alive at this moment. When the task_run-function is finished, the
destructor of the wrap-object is called, which in return calls the
destructor of the request-object again.

Instead of taking care of both, the request and the wrap-object, we can
move the request to the wrap which will then effectively take care of
the request object automatically.

Signed-off-by: Marian Cichy <m.cichy@pengutronix.de>
Suggested-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>
This commit is contained in:
Marian Cichy 2021-03-11 10:33:25 +01:00 • committed by Laurent Pinchart
parent f5d3fa1254
commit 80bebfb64e
1 changed files with 23 additions and 16 deletions
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39
src/gstreamer/gstlibcamerasrc.cpp
View file

@ -52,19 +52,18 @@ GST_DEBUG_CATEGORY_STATIC(source_debug);
#define GST_CAT_DEFAULT source_debug
struct RequestWrap {
RequestWrap(Request *request);
RequestWrap(std::unique_ptr<Request> request);
~RequestWrap();
void attachBuffer(GstBuffer *buffer);
GstBuffer *detachBuffer(Stream *stream);
/* For ptr comparison only. */
Request *request_;
std::unique_ptr<Request> request_;
std::map<Stream *, GstBuffer *> buffers_;
};
RequestWrap::RequestWrap(Request *request)
: request_(request)
RequestWrap::RequestWrap(std::unique_ptr<Request> request)
: request_(std::move(request))
{
}
@ -74,8 +73,6 @@ RequestWrap::~RequestWrap()
if (item.second)
gst_buffer_unref(item.second);
}
delete request_;
}
void RequestWrap::attachBuffer(GstBuffer *buffer)
@ -164,7 +161,7 @@ GstLibcameraSrcState::requestCompleted(Request *request)
std::unique_ptr<RequestWrap> wrap = std::move(requests_.front());
requests_.pop();
g_return_if_fail(wrap->request_ == request);
g_return_if_fail(wrap->request_.get() == request);
if ((request->status() == Request::RequestCancelled)) {
GST_DEBUG_OBJECT(src_, "Request was cancelled");
@ -269,7 +266,18 @@ gst_libcamera_src_task_run(gpointer user_data)
GstLibcameraSrcState *state = self->state;
std::unique_ptr<Request> request = state->cam_->createRequest();
auto wrap = std::make_unique<RequestWrap>(request.get());
if (!request) {
GST_ELEMENT_ERROR(self, RESOURCE, NO_SPACE_LEFT,
("Failed to allocate request for camera '%s'.",
state->cam_->id().c_str()),
("libcamera::Camera::createRequest() failed"));
gst_task_stop(self->task);
return;
}
std::unique_ptr<RequestWrap> wrap =
std::make_unique<RequestWrap>(std::move(request));
for (GstPad *srcpad : state->srcpads_) {
GstLibcameraPool *pool = gst_libcamera_pad_get_pool(srcpad);
GstBuffer *buffer;
@ -279,24 +287,23 @@ gst_libcamera_src_task_run(gpointer user_data)
&buffer, nullptr);
if (ret != GST_FLOW_OK) {
/*
* RequestWrap does not take ownership, and we won't be
* queueing this one due to lack of buffers.
* RequestWrap has ownership of the rquest, and we
* won't be queueing this one due to lack of buffers.
*/
request.reset();
wrap.release();
break;
}
wrap->attachBuffer(buffer);
}
if (request) {
if (wrap) {
GLibLocker lock(GST_OBJECT(self));
GST_TRACE_OBJECT(self, "Requesting buffers");
state->cam_->queueRequest(request.get());
state->cam_->queueRequest(wrap->request_.get());
state->requests_.push(std::move(wrap));
/* The request will be deleted in the completion handler. */
request.release();
/* The RequestWrap will be deleted in the completion handler. */
}
GstFlowReturn ret = GST_FLOW_OK;