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, 40 insertions, 0 deletions

diff --git a/arch/mips/bcm63xx/dev-rng.c b/arch/mips/bcm63xx/dev-rng.c
new file mode 100644
index 000000000..f94151f7c
--- /dev/null
+++ b/arch/mips/bcm63xx/dev-rng.c
@@ -0,0 +1,40 @@
+/*
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file "COPYING" in the main directory of this archive
+ * for more details.
+ *
+ * Copyright (C) 2011 Florian Fainelli <florian@openwrt.org>
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <bcm63xx_cpu.h>
+
+static struct resource rng_resources[] = {
+	{
+		.start		= -1, /* filled at runtime */
+		.end		= -1, /* filled at runtime */
+		.flags		= IORESOURCE_MEM,
+	},
+};
+
+static struct platform_device bcm63xx_rng_device = {
+	.name		= "bcm63xx-rng",
+	.id		= -1,
+	.num_resources	= ARRAY_SIZE(rng_resources),
+	.resource	= rng_resources,
+};
+
+static int __init bcm63xx_rng_register(void)
+{
+	if (!BCMCPU_IS_6368())
+		return -ENODEV;
+
+	rng_resources[0].start = bcm63xx_regset_address(RSET_RNG);
+	rng_resources[0].end = rng_resources[0].start;
+	rng_resources[0].end += RSET_RNG_SIZE - 1;
+
+	return platform_device_register(&bcm63xx_rng_device);
+}
+arch_initcall(bcm63xx_rng_register);