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, 54 insertions, 0 deletions

diff --git a/fs/ntfs/sysctl.c b/fs/ntfs/sysctl.c
new file mode 100644
index 000000000..8c5c1b7cd
--- /dev/null
+++ b/fs/ntfs/sysctl.c
@@ -0,0 +1,54 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Code for sysctl handling in NTFS Linux kernel driver.
+ *
+ * Copyright (C) 1997 Martin von Löwis, Régis Duchesne
+ * Copyright (c) 2002-2005 Anton Altaparmakov
+ */
+
+#ifdef DEBUG
+
+#include <linux/module.h>
+
+#ifdef CONFIG_SYSCTL
+
+#include <linux/proc_fs.h>
+#include <linux/sysctl.h>
+
+#include "sysctl.h"
+#include "debug.h"
+
+/* Definition of the ntfs sysctl. */
+static const struct ctl_table ntfs_sysctls[] = {
+	{
+		.procname	= "ntfs-debug",
+		.data		= &debug_msgs,		/* Data pointer and size. */
+		.maxlen		= sizeof(debug_msgs),
+		.mode		= 0644,			/* Mode, proc handler. */
+		.proc_handler	= proc_dointvec
+	},
+};
+
+/* Storage for the sysctls header. */
+static struct ctl_table_header *sysctls_root_table;
+
+/*
+ * ntfs_sysctl - add or remove the debug sysctl
+ * @add:	add (1) or remove (0) the sysctl
+ *
+ * Add or remove the debug sysctl. Return 0 on success or -errno on error.
+ */
+int ntfs_sysctl(int add)
+{
+	if (add) {
+		sysctls_root_table = register_sysctl("fs/ntfs", ntfs_sysctls);
+		if (!sysctls_root_table)
+			return -ENOMEM;
+	} else {
+		unregister_sysctl_table(sysctls_root_table);
+		sysctls_root_table = NULL;
+	}
+	return 0;
+}
+#endif /* CONFIG_SYSCTL */
+#endif /* DEBUG */