[PATCH][next] lkdtm: remove redundant initialization of ret

[PATCH][next] lkdtm: remove redundant initialization of ret

[Colin King]

From: Colin Ian King <colin.king@canonical.com>

The variable ret is being initialized with the value -EINVAL however
this value is never read and ret is being re-assigned later on. Hence
the initialization is redundant and can be removed.

Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
---
 drivers/misc/lkdtm/core.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
index bba093224813..92df35fdeab0 100644
--- a/drivers/misc/lkdtm/core.c
+++ b/drivers/misc/lkdtm/core.c
@@ -390,7 +390,7 @@ static int __init lkdtm_module_init(void)
 {
 	struct crashpoint *crashpoint = NULL;
 	const struct crashtype *crashtype = NULL;
-	int ret = -EINVAL;
+	int ret;
 	int i;
 
 	/* Neither or both of these need to be set */
-- 
2.20.1

Re: [PATCH][next] lkdtm: remove redundant initialization of ret

[Kees Cook]

On Fri, Jun 14, 2019 at 10:43:11AM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> The variable ret is being initialized with the value -EINVAL however
> this value is never read and ret is being re-assigned later on. Hence
> the initialization is redundant and can be removed.
> 
> Addresses-Coverity: ("Unused value")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>

Thanks!

Acked-by: Kees Cook <keescook@chromium.org>

Greg, can you take this please?

-Kees

> ---
>  drivers/misc/lkdtm/core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
> index bba093224813..92df35fdeab0 100644
> --- a/drivers/misc/lkdtm/core.c
> +++ b/drivers/misc/lkdtm/core.c
> @@ -390,7 +390,7 @@ static int __init lkdtm_module_init(void)
>  {
>  	struct crashpoint *crashpoint = NULL;
>  	const struct crashtype *crashtype = NULL;
> -	int ret = -EINVAL;
> +	int ret;
>  	int i;
>  
>  	/* Neither or both of these need to be set */
> -- 
> 2.20.1
> 

-- 
Kees Cook

Re: [PATCH][next] lkdtm: remove redundant initialization of ret

[Greg Kroah-Hartman]

On Thu, Jun 20, 2019 at 11:13:32AM -0700, Kees Cook wrote:
> On Fri, Jun 14, 2019 at 10:43:11AM +0100, Colin King wrote:
> > From: Colin Ian King <colin.king@canonical.com>
> > 
> > The variable ret is being initialized with the value -EINVAL however
> > this value is never read and ret is being re-assigned later on. Hence
> > the initialization is redundant and can be removed.
> > 
> > Addresses-Coverity: ("Unused value")
> > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> 
> Thanks!
> 
> Acked-by: Kees Cook <keescook@chromium.org>
> 
> Greg, can you take this please?

Will do, thanks.

greg k-h

Re: [PATCH][next] lkdtm: remove redundant initialization of ret

[Greg Kroah-Hartman]

On Fri, Jun 14, 2019 at 10:43:11AM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
> 
> The variable ret is being initialized with the value -EINVAL however
> this value is never read and ret is being re-assigned later on. Hence
> the initialization is redundant and can be removed.
> 
> Addresses-Coverity: ("Unused value")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> Acked-by: Kees Cook <keescook@chromium.org>
> ---
>  drivers/misc/lkdtm/core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
> index bba093224813..92df35fdeab0 100644
> --- a/drivers/misc/lkdtm/core.c
> +++ b/drivers/misc/lkdtm/core.c
> @@ -390,7 +390,7 @@ static int __init lkdtm_module_init(void)
>  {
>  	struct crashpoint *crashpoint = NULL;
>  	const struct crashtype *crashtype = NULL;
> -	int ret = -EINVAL;
> +	int ret;
>  	int i;
>  
>  	/* Neither or both of these need to be set */
> -- 
> 2.20.1
> 

With this patch now applied, I get this build warning:
drivers/misc/lkdtm/core.c: In function lkdtm_module_init:
drivers/misc/lkdtm/core.c:467:9: warning: ret may be used uninitialized in this function [-Wmaybe-uninitialized]
  return ret;
         ^~~

So are you _sure_ it shouldn't be initialized?

thanks,

greg k-h

Re: [PATCH][next] lkdtm: remove redundant initialization of ret

[Greg Kroah-Hartman]

On Fri, Jun 21, 2019 at 04:03:47PM +0200, Greg Kroah-Hartman wrote:
> On Fri, Jun 14, 2019 at 10:43:11AM +0100, Colin King wrote:
> > From: Colin Ian King <colin.king@canonical.com>
> > 
> > The variable ret is being initialized with the value -EINVAL however
> > this value is never read and ret is being re-assigned later on. Hence
> > the initialization is redundant and can be removed.
> > 
> > Addresses-Coverity: ("Unused value")
> > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> > Acked-by: Kees Cook <keescook@chromium.org>
> > ---
> >  drivers/misc/lkdtm/core.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
> > index bba093224813..92df35fdeab0 100644
> > --- a/drivers/misc/lkdtm/core.c
> > +++ b/drivers/misc/lkdtm/core.c
> > @@ -390,7 +390,7 @@ static int __init lkdtm_module_init(void)
> >  {
> >  	struct crashpoint *crashpoint = NULL;
> >  	const struct crashtype *crashtype = NULL;
> > -	int ret = -EINVAL;
> > +	int ret;
> >  	int i;
> >  
> >  	/* Neither or both of these need to be set */
> > -- 
> > 2.20.1
> > 
> 
> With this patch now applied, I get this build warning:
> drivers/misc/lkdtm/core.c: In function lkdtm_module_init:
> drivers/misc/lkdtm/core.c:467:9: warning: ret may be used uninitialized in this function [-Wmaybe-uninitialized]
>   return ret;
>          ^~~
> 
> So are you _sure_ it shouldn't be initialized?

In looking at the code in my tree, ret is used uninitialized with this
patch, so maybe coverity is wrong, or I don't have all of the needed
patches?

thanks,

greg k-h

Re: [PATCH][next] lkdtm: remove redundant initialization of ret

[Kees Cook]

On Fri, Jun 21, 2019 at 04:05:09PM +0200, Greg Kroah-Hartman wrote:
> On Fri, Jun 21, 2019 at 04:03:47PM +0200, Greg Kroah-Hartman wrote:
> > On Fri, Jun 14, 2019 at 10:43:11AM +0100, Colin King wrote:
> > > From: Colin Ian King <colin.king@canonical.com>
> > > 
> > > The variable ret is being initialized with the value -EINVAL however
> > > this value is never read and ret is being re-assigned later on. Hence
> > > the initialization is redundant and can be removed.
> > > 
> > > Addresses-Coverity: ("Unused value")
> > > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> > > Acked-by: Kees Cook <keescook@chromium.org>
> > > ---
> > >  drivers/misc/lkdtm/core.c | 2 +-
> > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > 
> > > diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
> > > index bba093224813..92df35fdeab0 100644
> > > --- a/drivers/misc/lkdtm/core.c
> > > +++ b/drivers/misc/lkdtm/core.c
> > > @@ -390,7 +390,7 @@ static int __init lkdtm_module_init(void)
> > >  {
> > >  	struct crashpoint *crashpoint = NULL;
> > >  	const struct crashtype *crashtype = NULL;
> > > -	int ret = -EINVAL;
> > > +	int ret;
> > >  	int i;
> > >  
> > >  	/* Neither or both of these need to be set */
> > > -- 
> > > 2.20.1
> > > 
> > 
> > With this patch now applied, I get this build warning:
> > drivers/misc/lkdtm/core.c: In function lkdtm_module_init:
> > drivers/misc/lkdtm/core.c:467:9: warning: ret may be used uninitialized in this function [-Wmaybe-uninitialized]
> >   return ret;
> >          ^~~
> > 
> > So are you _sure_ it shouldn't be initialized?
> 
> In looking at the code in my tree, ret is used uninitialized with this
> patch, so maybe coverity is wrong, or I don't have all of the needed
> patches?

The path went away when the check for debugfs_create_file() was removed.
I thought that patch was in your tree already?

In master, this is the path to "return ret" without prior assignment:

                de = debugfs_create_file(cur->name, 0644, lkdtm_debugfs_root,
                                         cur, &cur->fops);
                if (de = NULL) {
                        pr_err("could not create crashpoint %s\n", cur->name);
                        goto out_err;
                }


-- 
Kees Cook

Re: [PATCH][next] lkdtm: remove redundant initialization of ret

[Greg Kroah-Hartman]

On Fri, Jun 21, 2019 at 09:26:05AM -0700, Kees Cook wrote:
> On Fri, Jun 21, 2019 at 04:05:09PM +0200, Greg Kroah-Hartman wrote:
> > On Fri, Jun 21, 2019 at 04:03:47PM +0200, Greg Kroah-Hartman wrote:
> > > On Fri, Jun 14, 2019 at 10:43:11AM +0100, Colin King wrote:
> > > > From: Colin Ian King <colin.king@canonical.com>
> > > > 
> > > > The variable ret is being initialized with the value -EINVAL however
> > > > this value is never read and ret is being re-assigned later on. Hence
> > > > the initialization is redundant and can be removed.
> > > > 
> > > > Addresses-Coverity: ("Unused value")
> > > > Signed-off-by: Colin Ian King <colin.king@canonical.com>
> > > > Acked-by: Kees Cook <keescook@chromium.org>
> > > > ---
> > > >  drivers/misc/lkdtm/core.c | 2 +-
> > > >  1 file changed, 1 insertion(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/misc/lkdtm/core.c b/drivers/misc/lkdtm/core.c
> > > > index bba093224813..92df35fdeab0 100644
> > > > --- a/drivers/misc/lkdtm/core.c
> > > > +++ b/drivers/misc/lkdtm/core.c
> > > > @@ -390,7 +390,7 @@ static int __init lkdtm_module_init(void)
> > > >  {
> > > >  	struct crashpoint *crashpoint = NULL;
> > > >  	const struct crashtype *crashtype = NULL;
> > > > -	int ret = -EINVAL;
> > > > +	int ret;
> > > >  	int i;
> > > >  
> > > >  	/* Neither or both of these need to be set */
> > > > -- 
> > > > 2.20.1
> > > > 
> > > 
> > > With this patch now applied, I get this build warning:
> > > drivers/misc/lkdtm/core.c: In function lkdtm_module_init:
> > > drivers/misc/lkdtm/core.c:467:9: warning: ret may be used uninitialized in this function [-Wmaybe-uninitialized]
> > >   return ret;
> > >          ^~~
> > > 
> > > So are you _sure_ it shouldn't be initialized?
> > 
> > In looking at the code in my tree, ret is used uninitialized with this
> > patch, so maybe coverity is wrong, or I don't have all of the needed
> > patches?
> 
> The path went away when the check for debugfs_create_file() was removed.
> I thought that patch was in your tree already?

Ah, other tree, sorry, my fault.  I'll go queue this up to the place
that patch is...

thanks,

greg k-h