2016-09-05 16:21:18

by Colin King

Subject: [PATCH] s390/crypto: initialize ret to zero to avoid returning garbage value

From: Colin Ian King <[email protected]>

static analysis with cppcheck detected that ret is not initialized
and hence garbage is potentially being returned in the case where
prng_data->ppnows.reseed_counter <= prng_reseed_limit.

Signed-off-by: Colin Ian King <[email protected]>
---
arch/s390/crypto/prng.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/arch/s390/crypto/prng.c b/arch/s390/crypto/prng.c
index 79e3a1f..a21fdf4 100644
--- a/arch/s390/crypto/prng.c
+++ b/arch/s390/crypto/prng.c
@@ -412,7 +412,7 @@ static int prng_sha512_reseed(void)

static int prng_sha512_generate(u8 *buf, size_t nbytes)
{
- int ret;
+ int ret = 0;

/* reseed needed ? */
if (prng_data->ppnows.reseed_counter > prng_reseed_limit) {
--
2.9.3

2016-09-06 07:10:25

by Martin Schwidefsky

Subject: Re: [PATCH] s390/crypto: initialize ret to zero to avoid returning garbage value

On Mon, 5 Sep 2016 17:21:18 +0100
Colin King <[email protected]> wrote:

> From: Colin Ian King <[email protected]>
>
> static analysis with cppcheck detected that ret is not initialized
> and hence garbage is potentially being returned in the case where
> prng_data->ppnows.reseed_counter <= prng_reseed_limit.
>
> Signed-off-by: Colin Ian King <[email protected]>
> ---
> arch/s390/crypto/prng.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/s390/crypto/prng.c b/arch/s390/crypto/prng.c
> index 79e3a1f..a21fdf4 100644
> --- a/arch/s390/crypto/prng.c
> +++ b/arch/s390/crypto/prng.c
> @@ -412,7 +412,7 @@ static int prng_sha512_reseed(void)
>
> static int prng_sha512_generate(u8 *buf, size_t nbytes)
> {
> - int ret;
> + int ret = 0;
>
> /* reseed needed ? */
> if (prng_data->ppnows.reseed_counter > prng_reseed_limit) {

This issue has been introduced by git commit 0177db01adf26cf9
"s390/crypto: simplify return code handling" which is only on
the features branch right now. And to set ret=0 does not fix
the problem. The correct fix is to return nbytes.

Still a good catch though.

--
blue skies,
Martin.

"Reality continues to ruin my life." - Calvin.