selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 41 insertions, 0 deletions

diff --git a/sound/soc/samsung/dmaengine.c b/sound/soc/samsung/dmaengine.c
new file mode 100644
index 000000000..2802789a3
--- /dev/null
+++ b/sound/soc/samsung/dmaengine.c
@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0
+//
+// dmaengine.c - Samsung dmaengine wrapper
+//
+// Author: Mark Brown <broonie@linaro.org>
+// Copyright 2013 Linaro
+
+#include <linux/module.h>
+#include <sound/core.h>
+#include <sound/pcm.h>
+#include <sound/pcm_params.h>
+#include <sound/dmaengine_pcm.h>
+#include <sound/soc.h>
+
+#include "dma.h"
+
+int samsung_asoc_dma_platform_register(struct device *dev, dma_filter_fn filter,
+				       const char *tx, const char *rx,
+				       struct device *dma_dev)
+{
+	struct snd_dmaengine_pcm_config *pcm_conf;
+
+	pcm_conf = devm_kzalloc(dev, sizeof(*pcm_conf), GFP_KERNEL);
+	if (!pcm_conf)
+		return -ENOMEM;
+
+	pcm_conf->prepare_slave_config = snd_dmaengine_pcm_prepare_slave_config;
+	pcm_conf->compat_filter_fn = filter;
+	pcm_conf->dma_dev = dma_dev;
+
+	pcm_conf->chan_names[SNDRV_PCM_STREAM_PLAYBACK] = tx;
+	pcm_conf->chan_names[SNDRV_PCM_STREAM_CAPTURE] = rx;
+
+	return devm_snd_dmaengine_pcm_register(dev, pcm_conf,
+				SND_DMAENGINE_PCM_FLAG_COMPAT);
+}
+EXPORT_SYMBOL_GPL(samsung_asoc_dma_platform_register);
+
+MODULE_AUTHOR("Mark Brown <broonie@linaro.org>");
+MODULE_DESCRIPTION("Samsung dmaengine ASoC driver");
+MODULE_LICENSE("GPL");