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, 52 insertions, 0 deletions

diff --git a/fs/gfs2/trans.h b/fs/gfs2/trans.h
new file mode 100644
index 000000000..790c55f59
--- /dev/null
+++ b/fs/gfs2/trans.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
+ * Copyright (C) 2004-2006 Red Hat, Inc.  All rights reserved.
+ */
+
+#ifndef __TRANS_DOT_H__
+#define __TRANS_DOT_H__
+
+#include <linux/buffer_head.h>
+struct gfs2_sbd;
+struct gfs2_rgrpd;
+struct gfs2_glock;
+
+#define RES_DINODE	1
+#define RES_INDIRECT	1
+#define RES_JDATA	1
+#define RES_DATA	1
+#define RES_LEAF	1
+#define RES_RG_HDR	1
+#define RES_RG_BIT	2
+#define RES_EATTR	1
+#define RES_STATFS	1
+#define RES_QUOTA	2
+
+/* reserve either the number of blocks to be allocated plus the rg header
+ * block, or all of the blocks in the rg, whichever is smaller */
+static inline unsigned int gfs2_rg_blocks(const struct gfs2_inode *ip, unsigned requested)
+{
+	struct gfs2_rgrpd *rgd = ip->i_res.rs_rgd;
+
+	if (requested < rgd->rd_length)
+		return requested + 1;
+	return rgd->rd_length;
+}
+
+int __gfs2_trans_begin(struct gfs2_trans *tr, struct gfs2_sbd *sdp,
+		       unsigned int blocks, unsigned int revokes,
+		       unsigned long ip);
+int gfs2_trans_begin(struct gfs2_sbd *sdp, unsigned int blocks,
+		     unsigned int revokes);
+
+void gfs2_trans_end(struct gfs2_sbd *sdp);
+void gfs2_trans_add_data(struct gfs2_glock *gl, struct buffer_head *bh);
+void gfs2_trans_add_databufs(struct gfs2_glock *gl, struct folio *folio,
+			     size_t from, size_t len);
+void gfs2_trans_add_meta(struct gfs2_glock *gl, struct buffer_head *bh);
+void gfs2_trans_add_revoke(struct gfs2_sbd *sdp, struct gfs2_bufdata *bd);
+void gfs2_trans_remove_revoke(struct gfs2_sbd *sdp, u64 blkno, unsigned int len);
+void gfs2_trans_free(struct gfs2_sbd *sdp, struct gfs2_trans *tr);
+
+#endif /* __TRANS_DOT_H__ */