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, 64 insertions, 0 deletions

diff --git a/include/asm-generic/bitops/le.h b/include/asm-generic/bitops/le.h
new file mode 100644
index 000000000..d51beff60
--- /dev/null
+++ b/include/asm-generic/bitops/le.h
@@ -0,0 +1,64 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _ASM_GENERIC_BITOPS_LE_H_
+#define _ASM_GENERIC_BITOPS_LE_H_
+
+#include <asm/types.h>
+#include <asm/byteorder.h>
+
+#if defined(__LITTLE_ENDIAN)
+
+#define BITOP_LE_SWIZZLE	0
+
+#elif defined(__BIG_ENDIAN)
+
+#define BITOP_LE_SWIZZLE	((BITS_PER_LONG-1) & ~0x7)
+
+#endif
+
+
+static inline int test_bit_le(int nr, const void *addr)
+{
+	return test_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline void set_bit_le(int nr, void *addr)
+{
+	set_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline void clear_bit_le(int nr, void *addr)
+{
+	clear_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline void __set_bit_le(int nr, void *addr)
+{
+	__set_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline void __clear_bit_le(int nr, void *addr)
+{
+	__clear_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline int test_and_set_bit_le(int nr, void *addr)
+{
+	return test_and_set_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline int test_and_clear_bit_le(int nr, void *addr)
+{
+	return test_and_clear_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline int __test_and_set_bit_le(int nr, void *addr)
+{
+	return __test_and_set_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+static inline int __test_and_clear_bit_le(int nr, void *addr)
+{
+	return __test_and_clear_bit(nr ^ BITOP_LE_SWIZZLE, addr);
+}
+
+#endif /* _ASM_GENERIC_BITOPS_LE_H_ */