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, 26 insertions, 0 deletions

diff --git a/io_uring/uring_cmd.h b/io_uring/uring_cmd.h
new file mode 100644
index 000000000..041aef8a8
--- /dev/null
+++ b/io_uring/uring_cmd.h
@@ -0,0 +1,26 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/io_uring/cmd.h>
+#include <linux/io_uring_types.h>
+
+struct io_async_cmd {
+	struct iou_vec			vec;
+	struct io_uring_sqe		sqes[2];
+};
+
+int io_uring_cmd(struct io_kiocb *req, unsigned int issue_flags);
+int io_uring_cmd_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+void io_uring_cmd_sqe_copy(struct io_kiocb *req);
+void io_uring_cmd_cleanup(struct io_kiocb *req);
+
+bool io_uring_try_cancel_uring_cmd(struct io_ring_ctx *ctx,
+				   struct io_uring_task *tctx, bool cancel_all);
+
+bool io_uring_cmd_post_mshot_cqe32(struct io_uring_cmd *cmd,
+				   unsigned int issue_flags,
+				   struct io_uring_cqe cqe[2]);
+
+void io_cmd_cache_free(const void *entry);
+
+int io_cmd_poll_multishot(struct io_uring_cmd *cmd,
+			  unsigned int issue_flags, __poll_t mask);