linux-kernel - [PATCH 4.9 29/32] powerpc: Always initialize input array when calling epapr

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Date:   Mon,  4 Mar 2019 09:22:17 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Seth Forshee <seth.forshee@...onical.com>,
        Michael Ellerman <mpe@...erman.id.au>,
        "A. Wilcox" <awilfox@...lielinux.org>
Subject: [PATCH 4.9 29/32] powerpc: Always initialize input array when calling epapr_hypercall()

4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Seth Forshee <seth.forshee@...onical.com>

commit 186b8f1587c79c2fa04bfa392fdf084443e398c1 upstream.

Several callers to epapr_hypercall() pass an uninitialized stack
allocated array for the input arguments, presumably because they
have no input arguments. However this can produce errors like
this one

 arch/powerpc/include/asm/epapr_hcalls.h:470:42: error: 'in' may be used uninitialized in this function [-Werror=maybe-uninitialized]
  unsigned long register r3 asm("r3") = in[0];
                                        ~~^~~

Fix callers to this function to always zero-initialize the input
arguments array to prevent this.

Signed-off-by: Seth Forshee <seth.forshee@...onical.com>
Signed-off-by: Michael Ellerman <mpe@...erman.id.au>
Cc: "A. Wilcox" <awilfox@...lielinux.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 arch/powerpc/include/asm/epapr_hcalls.h |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

--- a/arch/powerpc/include/asm/epapr_hcalls.h
+++ b/arch/powerpc/include/asm/epapr_hcalls.h
@@ -508,7 +508,7 @@ static unsigned long epapr_hypercall(uns
 
 static inline long epapr_hypercall0_1(unsigned int nr, unsigned long *r2)
 {
-	unsigned long in[8];
+	unsigned long in[8] = {0};
 	unsigned long out[8];
 	unsigned long r;
 
@@ -520,7 +520,7 @@ static inline long epapr_hypercall0_1(un
 
 static inline long epapr_hypercall0(unsigned int nr)
 {
-	unsigned long in[8];
+	unsigned long in[8] = {0};
 	unsigned long out[8];
 
 	return epapr_hypercall(in, out, nr);
@@ -528,7 +528,7 @@ static inline long epapr_hypercall0(unsi
 
 static inline long epapr_hypercall1(unsigned int nr, unsigned long p1)
 {
-	unsigned long in[8];
+	unsigned long in[8] = {0};
 	unsigned long out[8];
 
 	in[0] = p1;
@@ -538,7 +538,7 @@ static inline long epapr_hypercall1(unsi
 static inline long epapr_hypercall2(unsigned int nr, unsigned long p1,
 				    unsigned long p2)
 {
-	unsigned long in[8];
+	unsigned long in[8] = {0};
 	unsigned long out[8];
 
 	in[0] = p1;
@@ -549,7 +549,7 @@ static inline long epapr_hypercall2(unsi
 static inline long epapr_hypercall3(unsigned int nr, unsigned long p1,
 				    unsigned long p2, unsigned long p3)
 {
-	unsigned long in[8];
+	unsigned long in[8] = {0};
 	unsigned long out[8];
 
 	in[0] = p1;
@@ -562,7 +562,7 @@ static inline long epapr_hypercall4(unsi
 				    unsigned long p2, unsigned long p3,
 				    unsigned long p4)
 {
-	unsigned long in[8];
+	unsigned long in[8] = {0};
 	unsigned long out[8];
 
 	in[0] = p1;