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, 43 insertions, 0 deletions

diff --git a/arch/mips/dec/reset.c b/arch/mips/dec/reset.c
new file mode 100644
index 000000000..ee1ad38f4
--- /dev/null
+++ b/arch/mips/dec/reset.c
@@ -0,0 +1,43 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Reset a DECstation machine.
+ *
+ * Copyright (C) 199x  the Anonymous
+ * Copyright (C) 2001, 2002, 2003  Maciej W. Rozycki
+ */
+#include <linux/interrupt.h>
+#include <linux/linkage.h>
+
+#include <asm/addrspace.h>
+
+#include <asm/dec/reset.h>
+
+typedef void __noreturn (* noret_func_t)(void);
+
+static inline void __noreturn back_to_prom(void)
+{
+	noret_func_t func = (void *)CKSEG1ADDR(0x1fc00000);
+
+	func();
+}
+
+void __noreturn dec_machine_restart(char *command)
+{
+	back_to_prom();
+}
+
+void __noreturn dec_machine_halt(void)
+{
+	back_to_prom();
+}
+
+void __noreturn dec_machine_power_off(void)
+{
+    /* DECstations don't have a software power switch */
+	back_to_prom();
+}
+
+irqreturn_t dec_intr_halt(int irq, void *dev_id)
+{
+	dec_machine_halt();
+}