linux-kernel - Re: [PATCH 05/12] s390: zcrypt: initialize variables before

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Date:   Mon, 8 Apr 2019 15:31:54 -0700
From:   Nathan Chancellor <natechancellor@...il.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Martin Schwidefsky <schwidefsky@...ibm.com>,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        Harald Freudenberger <freude@...ux.ibm.com>,
        clang-built-linux@...glegroups.com,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        linux-s390@...r.kernel.org, Ingo Franzki <ifranzki@...ibm.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 05/12] s390: zcrypt: initialize variables before_use

On Mon, Apr 08, 2019 at 11:26:18PM +0200, Arnd Bergmann wrote:
> The 'func_code' variable gets printed in debug statements without
> a prior initialization in multiple functions, as reported when building
> with clang:
> 
> drivers/s390/crypto/zcrypt_api.c:659:6: warning: variable 'func_code' is used uninitialized whenever 'if' condition is true
>       [-Wsometimes-uninitialized]
>         if (mex->outputdatalength < mex->inputdatalength) {
>             ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/s390/crypto/zcrypt_api.c:725:29: note: uninitialized use occurs here
>         trace_s390_zcrypt_rep(mex, func_code, rc,
>                                    ^~~~~~~~~
> drivers/s390/crypto/zcrypt_api.c:659:2: note: remove the 'if' if its condition is always false
>         if (mex->outputdatalength < mex->inputdatalength) {
>         ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> drivers/s390/crypto/zcrypt_api.c:654:24: note: initialize the variable 'func_code' to silence this warning
>         unsigned int func_code;
>                               ^
> 
> Add initializations to all affected code paths to shut up the warning
> and make the warning output consistent.
> 
> Signed-off-by: Arnd Bergmann <arnd@...db.de>

I'll never get used to seeing negative numbers assigned to unsigned
integers...

Reviewed-by: Nathan Chancellor <natechancellor@...il.com>

> ---
>  drivers/s390/crypto/zcrypt_api.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/s390/crypto/zcrypt_api.c b/drivers/s390/crypto/zcrypt_api.c
> index eb93c2d27d0a..23472063d9a8 100644
> --- a/drivers/s390/crypto/zcrypt_api.c
> +++ b/drivers/s390/crypto/zcrypt_api.c
> @@ -657,6 +657,7 @@ static long zcrypt_rsa_modexpo(struct ap_perms *perms,
>  	trace_s390_zcrypt_req(mex, TP_ICARSAMODEXPO);
>  
>  	if (mex->outputdatalength < mex->inputdatalength) {
> +		func_code = -1;
>  		rc = -EINVAL;
>  		goto out;
>  	}
> @@ -739,6 +740,7 @@ static long zcrypt_rsa_crt(struct ap_perms *perms,
>  	trace_s390_zcrypt_req(crt, TP_ICARSACRT);
>  
>  	if (crt->outputdatalength < crt->inputdatalength) {
> +		func_code = -1;
>  		rc = -EINVAL;
>  		goto out;
>  	}
> @@ -946,6 +948,7 @@ static long zcrypt_send_ep11_cprb(struct ap_perms *perms,
>  
>  		targets = kcalloc(target_num, sizeof(*targets), GFP_KERNEL);
>  		if (!targets) {
> +			func_code = -1;
>  			rc = -ENOMEM;
>  			goto out;
>  		}
> @@ -953,6 +956,7 @@ static long zcrypt_send_ep11_cprb(struct ap_perms *perms,
>  		uptr = (struct ep11_target_dev __force __user *) xcrb->targets;
>  		if (copy_from_user(targets, uptr,
>  				   target_num * sizeof(*targets))) {
> +			func_code = -1;
>  			rc = -EFAULT;
>  			goto out_free;
>  		}
> -- 
> 2.20.0
>