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/bitops.c | 69 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 69 insertions(+) create mode 100644 rust/helpers/bitops.c (limited to 'rust/helpers/bitops.c') diff --git a/rust/helpers/bitops.c b/rust/helpers/bitops.c new file mode 100644 index 000000000..271b8a712 --- /dev/null +++ b/rust/helpers/bitops.c @@ -0,0 +1,69 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include + +__rust_helper +void rust_helper___set_bit(unsigned long nr, unsigned long *addr) +{ + __set_bit(nr, addr); +} + +__rust_helper +void rust_helper___clear_bit(unsigned long nr, unsigned long *addr) +{ + __clear_bit(nr, addr); +} + +__rust_helper +void rust_helper_set_bit(unsigned long nr, volatile unsigned long *addr) +{ + set_bit(nr, addr); +} + +__rust_helper +void rust_helper_clear_bit(unsigned long nr, volatile unsigned long *addr) +{ + clear_bit(nr, addr); +} + +/* + * The rust_helper_ prefix is intentionally omitted below so that the + * declarations in include/linux/find.h are compatible with these helpers. + * + * Note that the below #ifdefs mean that the helper is only created if C does + * not provide a definition. + */ +#ifdef find_first_zero_bit +__rust_helper +unsigned long _find_first_zero_bit(const unsigned long *p, unsigned long size) +{ + return find_first_zero_bit(p, size); +} +#endif /* find_first_zero_bit */ + +#ifdef find_next_zero_bit +__rust_helper +unsigned long _find_next_zero_bit(const unsigned long *addr, + unsigned long size, unsigned long offset) +{ + return find_next_zero_bit(addr, size, offset); +} +#endif /* find_next_zero_bit */ + +#ifdef find_first_bit +__rust_helper +unsigned long _find_first_bit(const unsigned long *addr, unsigned long size) +{ + return find_first_bit(addr, size); +} +#endif /* find_first_bit */ + +#ifdef find_next_bit +__rust_helper +unsigned long _find_next_bit(const unsigned long *addr, unsigned long size, + unsigned long offset) +{ + return find_next_bit(addr, size, offset); +} +#endif /* find_next_bit */ -- cgit v1.3.1