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, 29 insertions, 0 deletions

diff --git a/arch/mips/ralink/bootrom.c b/arch/mips/ralink/bootrom.c
new file mode 100644
index 000000000..8c8cc0a81
--- /dev/null
+++ b/arch/mips/ralink/bootrom.c
@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *
+ * Copyright (C) 2013 John Crispin <john@phrozen.org>
+ */
+
+#include <linux/debugfs.h>
+#include <linux/seq_file.h>
+
+#define BOOTROM_OFFSET	0x10118000
+#define BOOTROM_SIZE	0x8000
+
+static void __iomem *membase = (void __iomem *) KSEG1ADDR(BOOTROM_OFFSET);
+
+static int bootrom_show(struct seq_file *s, void *unused)
+{
+	seq_write(s, membase, BOOTROM_SIZE);
+
+	return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(bootrom);
+
+static int __init bootrom_setup(void)
+{
+	debugfs_create_file("bootrom", 0444, NULL, NULL, &bootrom_fops);
+	return 0;
+}
+
+postcore_initcall(bootrom_setup);