From 6668ed271eaefaa63e686bdfbedaeb7b8e492722 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Fri, 4 Sep 2026 10:43:19 +0200 Subject: selftests/bpf: Reject graph kptr use after RCU unlock 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 Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- samples/trace_printk/Makefile | 7 +++++++ 1 file changed, 7 insertions(+) create mode 100644 samples/trace_printk/Makefile (limited to 'samples/trace_printk/Makefile') diff --git a/samples/trace_printk/Makefile b/samples/trace_printk/Makefile new file mode 100644 index 000000000..c0df36167 --- /dev/null +++ b/samples/trace_printk/Makefile @@ -0,0 +1,7 @@ +# SPDX-License-Identifier: GPL-2.0-only +# builds a module that calls various trace_printk routines +# then to use one (as root): insmod + +# This module can also be used to test the trace_printk code. + +obj-$(CONFIG_SAMPLE_TRACE_PRINTK) += trace-printk.o -- cgit v1.3.1