bpf: mark a NULL kfunc argument precisegrafted

check_kfunc_arg() allows bpf_register_is_null() for nullable arguments
w/o marking the underlying scalar register precise. Hence a checkpoint
created on such a path would prune against arbitrary scalar value.

Fixes: 3bda08b63670 ("bpf: Allow NULL buffers in bpf_dynptr_slice(_rw)")
Signed-off-by: Eduard Zingerman <eddyz87@gmail.com>
Link: https://lore.kernel.org/r/20260904-register-is-null-precise-fixes-v1-5-0f5a360ff15d@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 83 insertions, 0 deletions

diff --git a/fs/unicode/utf8n.h b/fs/unicode/utf8n.h
new file mode 100644
index 000000000..fc703aa4b
--- /dev/null
+++ b/fs/unicode/utf8n.h
@@ -0,0 +1,83 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (c) 2014 SGI.
+ * All rights reserved.
+ */
+
+#ifndef UTF8NORM_H
+#define UTF8NORM_H
+
+#include <linux/types.h>
+#include <linux/export.h>
+#include <linux/string.h>
+#include <linux/module.h>
+#include <linux/unicode.h>
+
+int utf8version_is_supported(const struct unicode_map *um, unsigned int version);
+
+/*
+ * Determine the length of the normalized from of the string,
+ * excluding any terminating NULL byte.
+ * Returns 0 if only ignorable code points are present.
+ * Returns -1 if the input is not valid UTF-8.
+ */
+ssize_t utf8nlen(const struct unicode_map *um, enum utf8_normalization n,
+		const char *s, size_t len);
+
+/* Needed in struct utf8cursor below. */
+#define UTF8HANGULLEAF	(12)
+
+/*
+ * Cursor structure used by the normalizer.
+ */
+struct utf8cursor {
+	const struct unicode_map *um;
+	enum utf8_normalization n;
+	const char	*s;
+	const char	*p;
+	const char	*ss;
+	const char	*sp;
+	unsigned int	len;
+	unsigned int	slen;
+	short int	ccc;
+	short int	nccc;
+	unsigned char	hangul[UTF8HANGULLEAF];
+};
+
+/*
+ * Initialize a utf8cursor to normalize a string.
+ * Returns 0 on success.
+ * Returns -1 on failure.
+ */
+int utf8ncursor(struct utf8cursor *u8c, const struct unicode_map *um,
+		enum utf8_normalization n, const char *s, size_t len);
+
+/*
+ * Get the next byte in the normalization.
+ * Returns a value > 0 && < 256 on success.
+ * Returns 0 when the end of the normalization is reached.
+ * Returns -1 if the string being normalized is not valid UTF-8.
+ */
+extern int utf8byte(struct utf8cursor *u8c);
+
+struct utf8data {
+	unsigned int maxage;
+	unsigned int offset;
+};
+
+struct utf8data_table {
+	const unsigned int *utf8agetab;
+	int utf8agetab_size;
+
+	const struct utf8data *utf8nfdicfdata;
+	int utf8nfdicfdata_size;
+
+	const struct utf8data *utf8nfdidata;
+	int utf8nfdidata_size;
+
+	const unsigned char *utf8data;
+};
+
+extern const struct utf8data_table utf8_data_table;
+
+#endif /* UTF8NORM_H */