[PATCH v1] devres: Fix devm_krealloc() allocating memory with wrong size

[PATCH v1] devres: Fix devm_krealloc() allocating memory with wrong size

[Zijun Hu]

Kernel API devm_krealloc() calls alloc_dr() with wrong argument
@total_new_size, and it will cause more memory to be allocated
than required, fixed by using @new_size as alloc_dr()'s argument.

Fixes: f82485722e5d ("devres: provide devm_krealloc()")
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
---
 drivers/base/devres.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/base/devres.c b/drivers/base/devres.c
index 3df0025d12aa..1cf87ddf1f55 100644
--- a/drivers/base/devres.c
+++ b/drivers/base/devres.c
@@ -898,7 +898,7 @@ void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp)
 	 * taking the lock as most probably the caller uses GFP_KERNEL.
 	 */
 	new_dr = alloc_dr(devm_kmalloc_release,
-			  total_new_size, gfp, dev_to_node(dev));
+			  new_size, gfp, dev_to_node(dev));
 	if (!new_dr)
 		return NULL;
 
-- 
2.7.4

Re: [PATCH v1] devres: Fix devm_krealloc() allocating memory with wrong size

[Greg KH]

On Sun, Jun 16, 2024 at 05:54:15PM +0800, Zijun Hu wrote:
> Kernel API devm_krealloc() calls alloc_dr() with wrong argument
> @total_new_size, and it will cause more memory to be allocated
> than required, fixed by using @new_size as alloc_dr()'s argument.
> 
> Fixes: f82485722e5d ("devres: provide devm_krealloc()")
> Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
> ---
>  drivers/base/devres.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/base/devres.c b/drivers/base/devres.c
> index 3df0025d12aa..1cf87ddf1f55 100644
> --- a/drivers/base/devres.c
> +++ b/drivers/base/devres.c
> @@ -898,7 +898,7 @@ void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp)
>  	 * taking the lock as most probably the caller uses GFP_KERNEL.
>  	 */
>  	new_dr = alloc_dr(devm_kmalloc_release,
> -			  total_new_size, gfp, dev_to_node(dev));
> +			  new_size, gfp, dev_to_node(dev));
>  	if (!new_dr)
>  		return NULL;
>  
> -- 
> 2.7.4
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- You have marked a patch with a "Fixes:" tag for a commit that is in an
  older released kernel, yet you do not have a cc: stable line in the
  signed-off-by area at all, which means that the patch will not be
  applied to any older kernel releases.  To properly fix this, please
  follow the documented rules in the
  Documentation/process/stable-kernel-rules.rst file for how to resolve
  this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot

Re: [PATCH v1] devres: Fix devm_krealloc() allocating memory with wrong size

[Greg KH]

On Sun, Jun 16, 2024 at 05:54:15PM +0800, Zijun Hu wrote:
> Kernel API devm_krealloc() calls alloc_dr() with wrong argument
> @total_new_size, and it will cause more memory to be allocated
> than required, fixed by using @new_size as alloc_dr()'s argument.
> 
> Fixes: f82485722e5d ("devres: provide devm_krealloc()")
> Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
> ---
>  drivers/base/devres.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/base/devres.c b/drivers/base/devres.c
> index 3df0025d12aa..1cf87ddf1f55 100644
> --- a/drivers/base/devres.c
> +++ b/drivers/base/devres.c
> @@ -898,7 +898,7 @@ void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp)
>  	 * taking the lock as most probably the caller uses GFP_KERNEL.
>  	 */
>  	new_dr = alloc_dr(devm_kmalloc_release,
> -			  total_new_size, gfp, dev_to_node(dev));
> +			  new_size, gfp, dev_to_node(dev));

Wait, are you sure?  Did you properly test this?  What is the actual
savings and how do you handle the fact that you are now not allocating
the space reserved for the devres structure itself?

thanks,

greg k-h

Re: [PATCH v1] devres: Fix devm_krealloc() allocating memory with wrong size

[quic_zijuhu]

On 6/16/2024 6:02 PM, Greg KH wrote:
> On Sun, Jun 16, 2024 at 05:54:15PM +0800, Zijun Hu wrote:
>> Kernel API devm_krealloc() calls alloc_dr() with wrong argument
>> @total_new_size, and it will cause more memory to be allocated
>> than required, fixed by using @new_size as alloc_dr()'s argument.
>>
>> Fixes: f82485722e5d ("devres: provide devm_krealloc()")
>> Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
>> ---
>>  drivers/base/devres.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/base/devres.c b/drivers/base/devres.c
>> index 3df0025d12aa..1cf87ddf1f55 100644
>> --- a/drivers/base/devres.c
>> +++ b/drivers/base/devres.c
>> @@ -898,7 +898,7 @@ void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp)
>>  	 * taking the lock as most probably the caller uses GFP_KERNEL.
>>  	 */
>>  	new_dr = alloc_dr(devm_kmalloc_release,
>> -			  total_new_size, gfp, dev_to_node(dev));
>> +			  new_size, gfp, dev_to_node(dev));
> 
> Wait, are you sure?  Did you properly test this?  What is the actual
> savings and how do you handle the fact that you are now not allocating
> the space reserved for the devres structure itself?
> 
sure even if i did not test it.
beware that alloc_dr() will call check_dr_size() to reserve space for
devres structure.

it will reserve the devres structure two times if using wrong
@total_new_size. it is obvious wrong.

> thanks,
> 
> greg k-h

Re: [PATCH v1] devres: Fix devm_krealloc() allocating memory with wrong size

[Greg KH]

On Sun, Jun 16, 2024 at 06:10:02PM +0800, quic_zijuhu wrote:
> On 6/16/2024 6:02 PM, Greg KH wrote:
> > On Sun, Jun 16, 2024 at 05:54:15PM +0800, Zijun Hu wrote:
> >> Kernel API devm_krealloc() calls alloc_dr() with wrong argument
> >> @total_new_size, and it will cause more memory to be allocated
> >> than required, fixed by using @new_size as alloc_dr()'s argument.
> >>
> >> Fixes: f82485722e5d ("devres: provide devm_krealloc()")
> >> Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
> >> ---
> >>  drivers/base/devres.c | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/base/devres.c b/drivers/base/devres.c
> >> index 3df0025d12aa..1cf87ddf1f55 100644
> >> --- a/drivers/base/devres.c
> >> +++ b/drivers/base/devres.c
> >> @@ -898,7 +898,7 @@ void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp)
> >>  	 * taking the lock as most probably the caller uses GFP_KERNEL.
> >>  	 */
> >>  	new_dr = alloc_dr(devm_kmalloc_release,
> >> -			  total_new_size, gfp, dev_to_node(dev));
> >> +			  new_size, gfp, dev_to_node(dev));
> > 
> > Wait, are you sure?  Did you properly test this?  What is the actual
> > savings and how do you handle the fact that you are now not allocating
> > the space reserved for the devres structure itself?
> > 
> sure even if i did not test it.
> beware that alloc_dr() will call check_dr_size() to reserve space for
> devres structure.
> 
> it will reserve the devres structure two times if using wrong
> @total_new_size. it is obvious wrong.

Ah, I missed that, that is tricky.  Please document this better when you
resubmit a new version.

And of course, please test it.

thanks,

greg k-h

Re: [PATCH v1] devres: Fix devm_krealloc() allocating memory with wrong size

[quic_zijuhu]

On 6/16/2024 6:17 PM, Greg KH wrote:
> On Sun, Jun 16, 2024 at 06:10:02PM +0800, quic_zijuhu wrote:
>> On 6/16/2024 6:02 PM, Greg KH wrote:
>>> On Sun, Jun 16, 2024 at 05:54:15PM +0800, Zijun Hu wrote:
>>>> Kernel API devm_krealloc() calls alloc_dr() with wrong argument
>>>> @total_new_size, and it will cause more memory to be allocated
>>>> than required, fixed by using @new_size as alloc_dr()'s argument.
>>>>
>>>> Fixes: f82485722e5d ("devres: provide devm_krealloc()")
>>>> Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
>>>> ---
>>>>  drivers/base/devres.c | 2 +-
>>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/base/devres.c b/drivers/base/devres.c
>>>> index 3df0025d12aa..1cf87ddf1f55 100644
>>>> --- a/drivers/base/devres.c
>>>> +++ b/drivers/base/devres.c
>>>> @@ -898,7 +898,7 @@ void *devm_krealloc(struct device *dev, void *ptr, size_t new_size, gfp_t gfp)
>>>>  	 * taking the lock as most probably the caller uses GFP_KERNEL.
>>>>  	 */
>>>>  	new_dr = alloc_dr(devm_kmalloc_release,
>>>> -			  total_new_size, gfp, dev_to_node(dev));
>>>> +			  new_size, gfp, dev_to_node(dev));
>>>
>>> Wait, are you sure?  Did you properly test this?  What is the actual
>>> savings and how do you handle the fact that you are now not allocating
>>> the space reserved for the devres structure itself?
>>>
>> sure even if i did not test it.
>> beware that alloc_dr() will call check_dr_size() to reserve space for
>> devres structure.
>>
>> it will reserve the devres structure two times if using wrong
>> @total_new_size. it is obvious wrong.
> 
> Ah, I missed that, that is tricky.  Please document this better when you
> resubmit a new version.
> 
okay. will send v2.
> And of course, please test it.
okay.
> 
> thanks,
> 
> greg k-h