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, 116 insertions, 0 deletions

diff --git a/fs/ntfs3/upcase.c b/fs/ntfs3/upcase.c
new file mode 100644
index 000000000..7681eefac
--- /dev/null
+++ b/fs/ntfs3/upcase.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ *
+ * Copyright (C) 2019-2021 Paragon Software GmbH, All rights reserved.
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/types.h>
+
+#include "ntfs_fs.h"
+
+static inline u16 upcase_unicode_char(const u16 *upcase, u16 chr)
+{
+	if (chr < 'a')
+		return chr;
+
+	if (chr <= 'z')
+		return chr - ('a' - 'A');
+
+	return upcase[chr];
+}
+
+/*
+ * ntfs_cmp_names
+ *
+ * Thanks Kari Argillander <kari.argillander@gmail.com> for idea and implementation 'bothcase'
+ *
+ * Straight way to compare names:
+ * - Case insensitive
+ * - If name equals and 'bothcases' then
+ * - Case sensitive
+ * 'Straight way' code scans input names twice in worst case.
+ * Optimized code scans input names only once.
+ */
+int ntfs_cmp_names(const __le16 *s1, size_t l1, const __le16 *s2, size_t l2,
+		   const u16 *upcase, bool bothcase)
+{
+	int diff1 = 0;
+	int diff2;
+	size_t len = min(l1, l2);
+
+	if (!bothcase && upcase)
+		goto case_insentive;
+
+	for (; len; s1++, s2++, len--) {
+		diff1 = le16_to_cpu(*s1) - le16_to_cpu(*s2);
+		if (diff1) {
+			if (bothcase && upcase)
+				goto case_insentive;
+
+			return diff1;
+		}
+	}
+	return l1 - l2;
+
+case_insentive:
+	for (; len; s1++, s2++, len--) {
+		diff2 = upcase_unicode_char(upcase, le16_to_cpu(*s1)) -
+			upcase_unicode_char(upcase, le16_to_cpu(*s2));
+		if (diff2)
+			return diff2;
+	}
+
+	diff2 = l1 - l2;
+	return diff2 ? diff2 : diff1;
+}
+
+int ntfs_cmp_names_cpu(const struct cpu_str *uni1, const struct le_str *uni2,
+		       const u16 *upcase, bool bothcase)
+{
+	const u16 *s1 = uni1->name;
+	const __le16 *s2 = uni2->name;
+	size_t l1 = uni1->len;
+	size_t l2 = uni2->len;
+	size_t len = min(l1, l2);
+	int diff1 = 0;
+	int diff2;
+
+	if (!bothcase && upcase)
+		goto case_insentive;
+
+	for (; len; s1++, s2++, len--) {
+		diff1 = *s1 - le16_to_cpu(*s2);
+		if (diff1) {
+			if (bothcase && upcase)
+				goto case_insentive;
+
+			return diff1;
+		}
+	}
+	return l1 - l2;
+
+case_insentive:
+	for (; len; s1++, s2++, len--) {
+		diff2 = upcase_unicode_char(upcase, *s1) -
+			upcase_unicode_char(upcase, le16_to_cpu(*s2));
+		if (diff2)
+			return diff2;
+	}
+
+	diff2 = l1 - l2;
+	return diff2 ? diff2 : diff1;
+}
+
+/* Helper function for ntfs_d_hash. */
+unsigned long ntfs_names_hash(const u16 *name, size_t len, const u16 *upcase,
+			      unsigned long hash)
+{
+	while (len--) {
+		unsigned int c = upcase_unicode_char(upcase, *name++);
+		hash = partial_name_hash(c, hash);
+	}
+
+	return hash;
+}