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 --- rust/helpers/refcount.c | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) create mode 100644 rust/helpers/refcount.c (limited to 'rust/helpers/refcount.c') diff --git a/rust/helpers/refcount.c b/rust/helpers/refcount.c new file mode 100644 index 000000000..36334a674 --- /dev/null +++ b/rust/helpers/refcount.c @@ -0,0 +1,28 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include + +__rust_helper refcount_t rust_helper_REFCOUNT_INIT(int n) +{ + return (refcount_t)REFCOUNT_INIT(n); +} + +__rust_helper void rust_helper_refcount_set(refcount_t *r, int n) +{ + refcount_set(r, n); +} + +__rust_helper void rust_helper_refcount_inc(refcount_t *r) +{ + refcount_inc(r); +} + +__rust_helper void rust_helper_refcount_dec(refcount_t *r) +{ + refcount_dec(r); +} + +__rust_helper bool rust_helper_refcount_dec_and_test(refcount_t *r) +{ + return refcount_dec_and_test(r); +} -- cgit v1.3.1