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, 102 insertions, 0 deletions

diff --git a/drivers/accessibility/speakup/utils.h b/drivers/accessibility/speakup/utils.h
new file mode 100644
index 000000000..4ce9a12f7
--- /dev/null
+++ b/drivers/accessibility/speakup/utils.h
@@ -0,0 +1,102 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/* utils.h
+ * originally written by: Kirk Reiser.
+ *
+ ** Copyright (C) 2002  Kirk Reiser.
+ *  Copyright (C) 2003  David Borowski.
+ */
+
+#include <stdio.h>
+
+#define MAXKEYS 512
+#define MAXKEYVAL 160
+#define HASHSIZE 101
+#define is_shift -3
+#define is_spk -2
+#define is_input -1
+
+struct st_key {
+	char *name;
+	struct st_key *next;
+	int value, shift;
+};
+
+struct st_key key_table[MAXKEYS];
+struct st_key *extra_keys = key_table+HASHSIZE;
+char *def_name, *def_val;
+FILE *infile;
+int lc;
+
+char filename[256];
+
+static inline void open_input(const char *dir_name, const char *name)
+{
+	if (dir_name)
+		snprintf(filename, sizeof(filename), "%s/%s", dir_name, name);
+	else
+		snprintf(filename, sizeof(filename), "%s", name);
+	infile = fopen(filename, "r");
+	if (infile == 0) {
+		fprintf(stderr, "can't open %s\n", filename);
+		exit(1);
+	}
+	lc = 0;
+}
+
+static inline int oops(const char *msg, const char *info)
+{
+	if (info == NULL)
+		info = "";
+	fprintf(stderr, "error: file %s line %d\n", filename, lc);
+	fprintf(stderr, "%s %s\n", msg, info);
+	exit(1);
+}
+
+static inline struct st_key *hash_name(char *name)
+{
+	unsigned char *pn = (unsigned char *)name;
+	int hash = 0;
+
+	while (*pn) {
+		hash = (hash * 17) & 0xfffffff;
+		if (isupper(*pn))
+			*pn = tolower(*pn);
+		hash += (int)*pn;
+		pn++;
+	}
+	hash %= HASHSIZE;
+	return &key_table[hash];
+}
+
+static inline struct st_key *find_key(char *name)
+{
+	struct st_key *this = hash_name(name);
+
+	while (this) {
+		if (this->name && !strcmp(name, this->name))
+			return this;
+		this = this->next;
+	}
+	return this;
+}
+
+static inline struct st_key *add_key(char *name, int value, int shift)
+{
+	struct st_key *this = hash_name(name);
+
+	if (extra_keys-key_table >= MAXKEYS)
+		oops("out of key table space, enlarge MAXKEYS", NULL);
+	if (this->name != NULL) {
+		while (this->next) {
+			if (!strcmp(name, this->name))
+				oops("attempt to add duplicate key", name);
+			this = this->next;
+		}
+		this->next = extra_keys++;
+		this = this->next;
+	}
+	this->name = strdup(name);
+	this->value = value;
+	this->shift = shift;
+	return this;
+}