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, 36 insertions, 0 deletions

diff --git a/block/partitions/atari.h b/block/partitions/atari.h
new file mode 100644
index 000000000..678202442
--- /dev/null
+++ b/block/partitions/atari.h
@@ -0,0 +1,36 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ *  fs/partitions/atari.h
+ *  Moved by Russell King from:
+ *
+ * linux/include/linux/atari_rootsec.h
+ * definitions for Atari Rootsector layout
+ * by Andreas Schwab (schwab@ls5.informatik.uni-dortmund.de)
+ *
+ * modified for ICD/Supra partitioning scheme restricted to at most 12
+ * partitions
+ * by Guenther Kelleter (guenther@pool.informatik.rwth-aachen.de)
+ */
+
+#include <linux/compiler.h>
+
+struct partition_info
+{
+  u8 flg;			/* bit 0: active; bit 7: bootable */
+  char id[3];			/* "GEM", "BGM", "XGM", or other */
+  __be32 st;			/* start of partition */
+  __be32 siz;			/* length of partition */
+};
+
+struct rootsector
+{
+  char unused[0x156];		/* room for boot code */
+  struct partition_info icdpart[8];	/* info for ICD-partitions 5..12 */
+  char unused2[0xc];
+  u32 hd_siz;			/* size of disk in blocks */
+  struct partition_info part[4];
+  u32 bsl_st;			/* start of bad sector list */
+  u32 bsl_cnt;			/* length of bad sector list */
+  u16 checksum;			/* checksum for bootable disks */
+} __packed;
+