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, 69 insertions, 0 deletions

diff --git a/fs/ubifs/misc.c b/fs/ubifs/misc.c
new file mode 100644
index 000000000..cd23de0f2
--- /dev/null
+++ b/fs/ubifs/misc.c
@@ -0,0 +1,69 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <linux/kernel.h>
+#include "ubifs.h"
+
+/* Normal UBIFS messages */
+void ubifs_msg(const struct ubifs_info *c, const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	pr_notice("UBIFS (ubi%d:%d): %pV\n",
+		  c->vi.ubi_num, c->vi.vol_id, &vaf);
+
+	va_end(args);
+}								    \
+
+/* UBIFS error messages */
+void ubifs_err(const struct ubifs_info *c, const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	pr_err("UBIFS error (ubi%d:%d pid %d): %ps: %pV\n",
+	       c->vi.ubi_num, c->vi.vol_id, current->pid,
+	       __builtin_return_address(0),
+	       &vaf);
+
+	va_end(args);
+}								    \
+
+/* UBIFS warning messages */
+void ubifs_warn(const struct ubifs_info *c, const char *fmt, ...)
+{
+	struct va_format vaf;
+	va_list args;
+
+	va_start(args, fmt);
+
+	vaf.fmt = fmt;
+	vaf.va = &args;
+
+	pr_warn("UBIFS warning (ubi%d:%d pid %d): %ps: %pV\n",
+		c->vi.ubi_num, c->vi.vol_id, current->pid,
+		__builtin_return_address(0),
+		&vaf);
+
+	va_end(args);
+}
+
+static char *assert_names[] = {
+	[ASSACT_REPORT] = "report",
+	[ASSACT_RO] = "read-only",
+	[ASSACT_PANIC] = "panic",
+};
+
+const char *ubifs_assert_action_name(struct ubifs_info *c)
+{
+	return assert_names[c->assert_action];
+}