[PATCH] powerpc: Always initialize input array when calling epapr_hypercall()

[PATCH] powerpc: Always initialize input array when calling epapr_hypercall()

[Seth Forshee]

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

diff --git a/arch/powerpc/include/asm/epapr_hcalls.h b/arch/powerpc/include/asm/epapr_hcalls.h
index 334459ad145b..90863245df53 100644
--- 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(unsigned long *in,
 
 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(unsigned int nr, unsigned long *r2)
 
 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(unsigned int nr)
 
 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(unsigned int nr, unsigned long p1)
 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(unsigned int nr, unsigned long p1,
 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(unsigned int nr, unsigned long p1,
 				    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;
-- 
2.14.1

Re: powerpc: Always initialize input array when calling epapr_hypercall()

[Michael Ellerman]

On Thu, 2017-09-28 at 13:33:39 UTC, Seth Forshee wrote:
> 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@canonical.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/186b8f1587c79c2fa04bfa392fdf08

cheers