[PATCH 1/2] drivers/of: Add check for null property in of_remove_property()

[PATCH 1/2] drivers/of: Add check for null property in of_remove_property()

[Suraj Jitindar Singh]

The validity of the property input argument to of_remove_property() is
never checked within the function and thus it is possible to pass a null
value. It happens that this will be picked up in __of_remove_property()
as no matching property of the device node will be found and thus an
error will be returned, however once again there is no explicit check
for a null value. By the time this is detected 2 locks have already been
acquired which is completely unnecessary if the property to remove is
null.

Add an explicit check in the function of_remove_property() for a null
property value and return -ENODEV in this case, this is consistent with
what the previous return value would have been when the null value was
not detected and passed to __of_remove_property().

By moving an explicit check for the property paramenter into the
of_remove_property() function, this will remove the need to perform this
check in calling code before invocation of the of_remove_property()
function.

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
---
 drivers/of/base.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index b299de2..64018eb 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1777,6 +1777,9 @@ int of_remove_property(struct device_node *np, struct property *prop)
 	unsigned long flags;
 	int rc;
 
+	if (!prop)
+		return -ENODEV;
+
 	mutex_lock(&of_mutex);
 
 	raw_spin_lock_irqsave(&devtree_lock, flags);
-- 
2.5.0

[PATCH 2/2] powerpc: Update of_remove_property() call sites to remove null checking

[Suraj Jitindar Singh]

After obtaining a property from of_find_property() and before calling
of_remove_property() most code checks to ensure that the property
returned from of_find_property() is not null. The previous patch
moved this check to the start of the function of_remove_property() in
order to avoid the case where this check isn't done and a null value is
passed. This ensures the check is always conducted before taking locks
and attempting to remove the property. Thus it is no longer necessary
to perform a check for null values before invoking of_remove_property().

Update of_remove_property() call sites in order to remove redundant
checking for null property value as check is now performed within the
of_remove_property function().

Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
---
 arch/powerpc/kernel/machine_kexec.c       | 19 ++++++-------------
 arch/powerpc/kernel/machine_kexec_64.c    | 11 ++++-------
 arch/powerpc/platforms/pseries/mobility.c |  4 ++--
 arch/powerpc/platforms/pseries/reconfig.c |  5 +----
 4 files changed, 13 insertions(+), 26 deletions(-)

diff --git a/arch/powerpc/kernel/machine_kexec.c b/arch/powerpc/kernel/machine_kexec.c
index 015ae55..55744a8 100644
--- a/arch/powerpc/kernel/machine_kexec.c
+++ b/arch/powerpc/kernel/machine_kexec.c
@@ -228,17 +228,12 @@ static struct property memory_limit_prop = {
 
 static void __init export_crashk_values(struct device_node *node)
 {
-	struct property *prop;
-
 	/* There might be existing crash kernel properties, but we can't
 	 * be sure what's in them, so remove them. */
-	prop = of_find_property(node, "linux,crashkernel-base", NULL);
-	if (prop)
-		of_remove_property(node, prop);
-
-	prop = of_find_property(node, "linux,crashkernel-size", NULL);
-	if (prop)
-		of_remove_property(node, prop);
+	of_remove_property(node, of_find_property(node,
+				"linux,crashkernel-base", NULL));
+	of_remove_property(node, of_find_property(node,
+				"linux,crashkernel-size", NULL));
 
 	if (crashk_res.start != 0) {
 		crashk_base = cpu_to_be_ulong(crashk_res.start),
@@ -258,16 +253,14 @@ static void __init export_crashk_values(struct device_node *node)
 static int __init kexec_setup(void)
 {
 	struct device_node *node;
-	struct property *prop;
 
 	node = of_find_node_by_path("/chosen");
 	if (!node)
 		return -ENOENT;
 
 	/* remove any stale properties so ours can be found */
-	prop = of_find_property(node, kernel_end_prop.name, NULL);
-	if (prop)
-		of_remove_property(node, prop);
+	of_remove_property(node, of_find_property(node, kernel_end_prop.name,
+				NULL));
 
 	/* information needed by userspace when using default_machine_kexec */
 	kernel_end = cpu_to_be_ulong(__pa(_end));
diff --git a/arch/powerpc/kernel/machine_kexec_64.c b/arch/powerpc/kernel/machine_kexec_64.c
index 0fbd75d..2608192 100644
--- a/arch/powerpc/kernel/machine_kexec_64.c
+++ b/arch/powerpc/kernel/machine_kexec_64.c
@@ -401,7 +401,6 @@ static struct property htab_size_prop = {
 static int __init export_htab_values(void)
 {
 	struct device_node *node;
-	struct property *prop;
 
 	/* On machines with no htab htab_address is NULL */
 	if (!htab_address)
@@ -412,12 +411,10 @@ static int __init export_htab_values(void)
 		return -ENODEV;
 
 	/* remove any stale propertys so ours can be found */
-	prop = of_find_property(node, htab_base_prop.name, NULL);
-	if (prop)
-		of_remove_property(node, prop);
-	prop = of_find_property(node, htab_size_prop.name, NULL);
-	if (prop)
-		of_remove_property(node, prop);
+	of_remove_property(node, of_find_property(node, htab_base_prop.name,
+				NULL));
+	of_remove_property(node, of_find_property(node, htab_size_prop.name,
+				NULL));
 
 	htab_base = cpu_to_be64(__pa(htab_address));
 	of_add_property(node, &htab_base_prop);
diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
index ceb18d3..a560a98 100644
--- a/arch/powerpc/platforms/pseries/mobility.c
+++ b/arch/powerpc/platforms/pseries/mobility.c
@@ -191,8 +191,8 @@ static int update_dt_node(__be32 phandle, s32 scope)
 				break;
 
 			case 0x80000000:
-				prop = of_find_property(dn, prop_name, NULL);
-				of_remove_property(dn, prop);
+				of_remove_property(dn, of_find_property(dn,
+							prop_name, NULL));
 				prop = NULL;
 				break;
 
diff --git a/arch/powerpc/platforms/pseries/reconfig.c b/arch/powerpc/platforms/pseries/reconfig.c
index 7c7fcc0..cc66c49 100644
--- a/arch/powerpc/platforms/pseries/reconfig.c
+++ b/arch/powerpc/platforms/pseries/reconfig.c
@@ -303,7 +303,6 @@ static int do_remove_property(char *buf, size_t bufsize)
 {
 	struct device_node *np;
 	char *tmp;
-	struct property *prop;
 	buf = parse_node(buf, bufsize, &np);
 
 	if (!np)
@@ -316,9 +315,7 @@ static int do_remove_property(char *buf, size_t bufsize)
 	if (strlen(buf) == 0)
 		return -EINVAL;
 
-	prop = of_find_property(np, buf, NULL);
-
-	return of_remove_property(np, prop);
+	return of_remove_property(np, of_find_property(np, buf, NULL));
 }
 
 static int do_update_property(char *buf, size_t bufsize)
-- 
2.5.0

Re: [PATCH 2/2] powerpc: Update of_remove_property() call sites to remove null checking

[Tyrel Datwyler]

On 04/27/2016 10:34 PM, Suraj Jitindar Singh wrote:
> After obtaining a property from of_find_property() and before calling
> of_remove_property() most code checks to ensure that the property
> returned from of_find_property() is not null. The previous patch
> moved this check to the start of the function of_remove_property() in
> order to avoid the case where this check isn't done and a null value is
> passed. This ensures the check is always conducted before taking locks
> and attempting to remove the property. Thus it is no longer necessary
> to perform a check for null values before invoking of_remove_property().
> 
> Update of_remove_property() call sites in order to remove redundant
> checking for null property value as check is now performed within the
> of_remove_property function().
> 
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> ---
>  arch/powerpc/kernel/machine_kexec.c       | 19 ++++++-------------
>  arch/powerpc/kernel/machine_kexec_64.c    | 11 ++++-------
>  arch/powerpc/platforms/pseries/mobility.c |  4 ++--
>  arch/powerpc/platforms/pseries/reconfig.c |  5 +----
>  4 files changed, 13 insertions(+), 26 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/machine_kexec.c b/arch/powerpc/kernel/machine_kexec.c
> index 015ae55..55744a8 100644
> --- a/arch/powerpc/kernel/machine_kexec.c
> +++ b/arch/powerpc/kernel/machine_kexec.c
> @@ -228,17 +228,12 @@ static struct property memory_limit_prop = {
>  
>  static void __init export_crashk_values(struct device_node *node)
>  {
> -	struct property *prop;
> -
>  	/* There might be existing crash kernel properties, but we can't
>  	 * be sure what's in them, so remove them. */
> -	prop = of_find_property(node, "linux,crashkernel-base", NULL);
> -	if (prop)
> -		of_remove_property(node, prop);
> -
> -	prop = of_find_property(node, "linux,crashkernel-size", NULL);
> -	if (prop)
> -		of_remove_property(node, prop);
> +	of_remove_property(node, of_find_property(node,
> +				"linux,crashkernel-base", NULL));
> +	of_remove_property(node, of_find_property(node,
> +				"linux,crashkernel-size", NULL));
>  
>  	if (crashk_res.start != 0) {
>  		crashk_base = cpu_to_be_ulong(crashk_res.start),
> @@ -258,16 +253,14 @@ static void __init export_crashk_values(struct device_node *node)
>  static int __init kexec_setup(void)
>  {
>  	struct device_node *node;
> -	struct property *prop;
>  
>  	node = of_find_node_by_path("/chosen");
>  	if (!node)
>  		return -ENOENT;
>  
>  	/* remove any stale properties so ours can be found */
> -	prop = of_find_property(node, kernel_end_prop.name, NULL);
> -	if (prop)
> -		of_remove_property(node, prop);
> +	of_remove_property(node, of_find_property(node, kernel_end_prop.name,
> +				NULL));
>  
>  	/* information needed by userspace when using default_machine_kexec */
>  	kernel_end = cpu_to_be_ulong(__pa(_end));
> diff --git a/arch/powerpc/kernel/machine_kexec_64.c b/arch/powerpc/kernel/machine_kexec_64.c
> index 0fbd75d..2608192 100644
> --- a/arch/powerpc/kernel/machine_kexec_64.c
> +++ b/arch/powerpc/kernel/machine_kexec_64.c
> @@ -401,7 +401,6 @@ static struct property htab_size_prop = {
>  static int __init export_htab_values(void)
>  {
>  	struct device_node *node;
> -	struct property *prop;
>  
>  	/* On machines with no htab htab_address is NULL */
>  	if (!htab_address)
> @@ -412,12 +411,10 @@ static int __init export_htab_values(void)
>  		return -ENODEV;
>  
>  	/* remove any stale propertys so ours can be found */
> -	prop = of_find_property(node, htab_base_prop.name, NULL);
> -	if (prop)
> -		of_remove_property(node, prop);
> -	prop = of_find_property(node, htab_size_prop.name, NULL);
> -	if (prop)
> -		of_remove_property(node, prop);
> +	of_remove_property(node, of_find_property(node, htab_base_prop.name,
> +				NULL));
> +	of_remove_property(node, of_find_property(node, htab_size_prop.name,
> +				NULL));
>  
>  	htab_base = cpu_to_be64(__pa(htab_address));
>  	of_add_property(node, &htab_base_prop);
> diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
> index ceb18d3..a560a98 100644
> --- a/arch/powerpc/platforms/pseries/mobility.c
> +++ b/arch/powerpc/platforms/pseries/mobility.c
> @@ -191,8 +191,8 @@ static int update_dt_node(__be32 phandle, s32 scope)
>  				break;
>  
>  			case 0x80000000:
> -				prop = of_find_property(dn, prop_name, NULL);
> -				of_remove_property(dn, prop);
> +				of_remove_property(dn, of_find_property(dn,
> +							prop_name, NULL));
>  				prop = NULL;
>  				break;
>

You haven't removed a NULL check here, as suggested by the changelog,
but instead made a cosmetic change to the code that still leaves behind
a now unnecessary "prop = NULL;" to bit rot.

> diff --git a/arch/powerpc/platforms/pseries/reconfig.c b/arch/powerpc/platforms/pseries/reconfig.c
> index 7c7fcc0..cc66c49 100644
> --- a/arch/powerpc/platforms/pseries/reconfig.c
> +++ b/arch/powerpc/platforms/pseries/reconfig.c
> @@ -303,7 +303,6 @@ static int do_remove_property(char *buf, size_t bufsize)
>  {
>  	struct device_node *np;
>  	char *tmp;
> -	struct property *prop;
>  	buf = parse_node(buf, bufsize, &np);
>  
>  	if (!np)
> @@ -316,9 +315,7 @@ static int do_remove_property(char *buf, size_t bufsize)
>  	if (strlen(buf) == 0)
>  		return -EINVAL;
>  
> -	prop = of_find_property(np, buf, NULL);
> -
> -	return of_remove_property(np, prop);
> +	return of_remove_property(np, of_find_property(np, buf, NULL));
>  }

Again, you are not removing a NULL check as suggested by the changelog.

-Tyrel

>  
>  static int do_update_property(char *buf, size_t bufsize)
> 

Re: [PATCH 2/2] powerpc: Update of_remove_property() call sites to remove null checking

[Michael Ellerman]

On Tue, 2016-05-03 at 15:32 -0700, Tyrel Datwyler wrote:
> On 04/27/2016 10:34 PM, Suraj Jitindar Singh wrote:
> > diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
> > index ceb18d3..a560a98 100644
> > --- a/arch/powerpc/platforms/pseries/mobility.c
> > +++ b/arch/powerpc/platforms/pseries/mobility.c
> > @@ -191,8 +191,8 @@ static int update_dt_node(__be32 phandle, s32 scope)
> >  				break;
> >  
> >  			case 0x80000000:
> > -				prop = of_find_property(dn, prop_name, NULL);
> > -				of_remove_property(dn, prop);
> > +				of_remove_property(dn, of_find_property(dn,
> > +							prop_name, NULL));
> >  				prop = NULL;
> >  				break;
> > 
> 
> You haven't removed a NULL check here, as suggested by the changelog,
> but instead made a cosmetic change to the code that still leaves behind
> a now unnecessary "prop = NULL;" to bit rot.

Yeah I think you're right. Though it's not very clear how prop is used in that
function.

Please one of you send me an incremental to remove the prop = NULL;

cheers

Re: [PATCH 2/2] powerpc: Update of_remove_property() call sites to remove null checking

[Suraj Jitindar Singh]

[-- Attachment #1: Type: text/plain, Size: 1383 bytes --]



On 05/05/16 16:50, Michael Ellerman wrote:
> On Tue, 2016-05-03 at 15:32 -0700, Tyrel Datwyler wrote: >> On 04/27/2016 10:34 PM, Suraj Jitindar Singh wrote: >>> diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c >>> index ceb18d3..a560a98 100644 >>> --- a/arch/powerpc/platforms/pseries/mobility.c >>> +++ b/arch/powerpc/platforms/pseries/mobility.c >>> @@ -191,8 +191,8 @@ static int update_dt_node(__be32 phandle, s32 scope) >>>                  break; >>>  >>>              case 0x80000000: >>> -                prop = of_find_property(dn, prop_name, NULL); >>> -                of_remove_property(dn, prop); >>> +                of_remove_property(dn, of_find_property(dn, >>> +                            prop_name, NULL)); >>>                  prop = NULL; >>>                  break; >>> >> >> You haven't removed a NULL check here, as suggested by the changelog, >> but instead made a cosmetic change to the code that still leaves behind >> a now unnecessary "prop = NULL;" to bit rot. > > Yeah I think you're right. Though it's not
very clear how prop is used in that > function. > > Please one of you send me an incremental to remove the prop = NULL; > > cheers >

I didn't delete the prop = NULL; initially as I didn't fully understand
how it was used in the rest of the function and the effect of deleting
it.


[-- Attachment #2: Type: text/html, Size: 1950 bytes --]

Re: [PATCH 2/2] powerpc: Update of_remove_property() call sites to remove null checking

[Suraj Jitindar Singh]

On 05/05/16 16:50, Michael Ellerman wrote:
> On Tue, 2016-05-03 at 15:32 -0700, Tyrel Datwyler wrote:
>> On 04/27/2016 10:34 PM, Suraj Jitindar Singh wrote:
>>> diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
>>> index ceb18d3..a560a98 100644
>>> --- a/arch/powerpc/platforms/pseries/mobility.c
>>> +++ b/arch/powerpc/platforms/pseries/mobility.c
>>> @@ -191,8 +191,8 @@ static int update_dt_node(__be32 phandle, s32 scope)
>>>  				break;
>>>  
>>>  			case 0x80000000:
>>> -				prop = of_find_property(dn, prop_name, NULL);
>>> -				of_remove_property(dn, prop);
>>> +				of_remove_property(dn, of_find_property(dn,
>>> +							prop_name, NULL));
>>>  				prop = NULL;
>>>  				break;
>>>
>> You haven't removed a NULL check here, as suggested by the changelog,
>> but instead made a cosmetic change to the code that still leaves behind
>> a now unnecessary "prop = NULL;" to bit rot.
> Yeah I think you're right. Though it's not very clear how prop is used in that
> function.
>
> Please one of you send me an incremental to remove the prop = NULL;
>
> cheers
>

Resend of previous message due to formatting issues:

I didn't delete the prop = NULL; initially as I didn't fully understand
how it was used in the rest of the function and the effect of deleting
it.

Re: [PATCH 2/2] powerpc: Update of_remove_property() call sites to remove null checking

[Michael Ellerman]

On Fri, 2016-05-06 at 13:00 +1000, Suraj Jitindar Singh wrote:
> On 05/05/16 16:50, Michael Ellerman wrote:
> > On Tue, 2016-05-03 at 15:32 -0700, Tyrel Datwyler wrote:
> > > On 04/27/2016 10:34 PM, Suraj Jitindar Singh wrote:
> > > > diff --git a/arch/powerpc/platforms/pseries/mobility.c b/arch/powerpc/platforms/pseries/mobility.c
> > > > index ceb18d3..a560a98 100644
> > > > --- a/arch/powerpc/platforms/pseries/mobility.c
> > > > +++ b/arch/powerpc/platforms/pseries/mobility.c
> > > > @@ -191,8 +191,8 @@ static int update_dt_node(__be32 phandle, s32 scope)
> > > >  				break;
> > > >  
> > > >  			case 0x80000000:
> > > > -				prop = of_find_property(dn, prop_name, NULL);
> > > > -				of_remove_property(dn, prop);
> > > > +				of_remove_property(dn, of_find_property(dn,
> > > > +							prop_name, NULL));
> > > >  				prop = NULL;
> > > >  				break;
> > > > 
> > > You haven't removed a NULL check here, as suggested by the changelog,
> > > but instead made a cosmetic change to the code that still leaves behind
> > > a now unnecessary "prop = NULL;" to bit rot.

> > Yeah I think you're right. Though it's not very clear how prop is used in that
> > function.
>
> I didn't delete the prop = NULL; initially as I didn't fully understand
> how it was used in the rest of the function and the effect of deleting
> it.

Yeah, it's pretty convoluted. I don't think you can actually prove it's safe to
remove the prop = NULL for arbitrary inputs.

cheers

Re: [2/2] powerpc: Update of_remove_property() call sites to remove null checking

[Michael Ellerman]

On Thu, 2016-28-04 at 05:34:55 UTC, Suraj Jitindar Singh wrote:
> After obtaining a property from of_find_property() and before calling
> of_remove_property() most code checks to ensure that the property
> returned from of_find_property() is not null. The previous patch
> moved this check to the start of the function of_remove_property() in
> order to avoid the case where this check isn't done and a null value is
> passed. This ensures the check is always conducted before taking locks
> and attempting to remove the property. Thus it is no longer necessary
> to perform a check for null values before invoking of_remove_property().
> 
> Update of_remove_property() call sites in order to remove redundant
> checking for null property value as check is now performed within the
> of_remove_property function().
> 
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/676669b666574a23f7bd62870c

cheers

Re: [PATCH 1/2] drivers/of: Add check for null property in of_remove_property()

[Rob Herring]

On Thu, Apr 28, 2016 at 12:34 AM, Suraj Jitindar Singh
<sjitindarsingh@gmail.com> wrote:
> The validity of the property input argument to of_remove_property() is
> never checked within the function and thus it is possible to pass a null
> value. It happens that this will be picked up in __of_remove_property()
> as no matching property of the device node will be found and thus an
> error will be returned, however once again there is no explicit check
> for a null value. By the time this is detected 2 locks have already been
> acquired which is completely unnecessary if the property to remove is
> null.
>
> Add an explicit check in the function of_remove_property() for a null
> property value and return -ENODEV in this case, this is consistent with
> what the previous return value would have been when the null value was
> not detected and passed to __of_remove_property().
>
> By moving an explicit check for the property paramenter into the
> of_remove_property() function, this will remove the need to perform this
> check in calling code before invocation of the of_remove_property()
> function.
>
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>

For both patches:

Acked-by: Rob Herring <robh@kernel.org>

Re: [1/2] drivers/of: Add check for null property in of_remove_property()

[Michael Ellerman]

On Thu, 2016-28-04 at 05:34:54 UTC, Suraj Jitindar Singh wrote:
> The validity of the property input argument to of_remove_property() is
> never checked within the function and thus it is possible to pass a null
> value. It happens that this will be picked up in __of_remove_property()
> as no matching property of the device node will be found and thus an
> error will be returned, however once again there is no explicit check
> for a null value. By the time this is detected 2 locks have already been
> acquired which is completely unnecessary if the property to remove is
> null.
> 
> Add an explicit check in the function of_remove_property() for a null
> property value and return -ENODEV in this case, this is consistent with
> what the previous return value would have been when the null value was
> not detected and passed to __of_remove_property().
> 
> By moving an explicit check for the property paramenter into the
> of_remove_property() function, this will remove the need to perform this
> check in calling code before invocation of the of_remove_property()
> function.
> 
> Signed-off-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
> Acked-by: Rob Herring <robh@kernel.org>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/1c173cb23486f540ea08a5050a

cheers