[PATCH 14/14] powerpc/rtas: Consolidate and improve checking for rtas callers

[Nicholas Piggin <npiggin@gmail.com>]

Add range checking from the rtas syscall, and other error checks
and warnings to kernel callers, so problems can be found and
fixed.

Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
---
 arch/powerpc/kernel/rtas.c | 23 +++++++++++++++++------
 1 file changed, 17 insertions(+), 6 deletions(-)

diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index adf4892aeecd..7f8a3fd685f9 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -428,6 +428,23 @@ static int notrace va_raw_rtas_call(struct rtas_args *args, int token,
 {
 	int i;
 
+	if (!irqs_disabled()) {
+		WARN_ON_ONCE(1);
+		return -1;
+	}
+
+	if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE) {
+		WARN_ON_ONCE(1);
+		return -1;
+	}
+
+	if (nargs >= ARRAY_SIZE(args->args)
+	    || nret > ARRAY_SIZE(args->args)
+	    || nargs + nret > ARRAY_SIZE(args->args)) {
+		WARN_ON_ONCE(1);
+		return -1;
+	}
+
 	args->token = cpu_to_be32(token);
 	args->nargs = cpu_to_be32(nargs);
 	args->nret  = cpu_to_be32(nret);
@@ -476,9 +493,6 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...)
 	char *buff_copy = NULL;
 	int ret;
 
-	if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
-		return -1;
-
 	if ((mfmsr() & (MSR_IR|MSR_DR)) != (MSR_IR|MSR_DR)) {
 		WARN_ON_ONCE(1);
 		return -1;
@@ -955,9 +969,6 @@ int rtas_call_reentrant(int token, int nargs, int nret, int *outputs, ...)
 	unsigned long flags;
 	int ret;
 
-	if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE)
-		return -1;
-
 	local_irq_save(flags);
 	preempt_disable();
 
-- 
2.23.0