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/drivers/soc/microchip/mpfs-control-scb.c b/drivers/soc/microchip/mpfs-control-scb.c
new file mode 100644
index 000000000..8dda5704a
--- /dev/null
+++ b/drivers/soc/microchip/mpfs-control-scb.c
@@ -0,0 +1,40 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/array_size.h>
+#include <linux/of.h>
+#include <linux/mfd/core.h>
+#include <linux/mfd/syscon.h>
+#include <linux/platform_device.h>
+
+static const struct mfd_cell mpfs_control_scb_devs[] = {
+	MFD_CELL_NAME("mpfs-tvs"),
+};
+
+static int mpfs_control_scb_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+
+	return devm_mfd_add_devices(dev, PLATFORM_DEVID_NONE,
+				    mpfs_control_scb_devs,
+				    ARRAY_SIZE(mpfs_control_scb_devs), NULL, 0,
+				    NULL);
+}
+
+static const struct of_device_id mpfs_control_scb_of_match[] = {
+	{ .compatible = "microchip,mpfs-control-scb", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, mpfs_control_scb_of_match);
+
+static struct platform_driver mpfs_control_scb_driver = {
+	.driver = {
+		.name = "mpfs-control-scb",
+		.of_match_table = mpfs_control_scb_of_match,
+	},
+	.probe = mpfs_control_scb_probe,
+};
+module_platform_driver(mpfs_control_scb_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Conor Dooley <conor.dooley@microchip.com>");
+MODULE_DESCRIPTION("PolarFire SoC control scb driver");