Re: [PATCH v1] devres: Fix devm_krealloc() allocating memory with wrong size
From: quic_zijuhu
Date: Sun Jun 16 2024 - 06:10:20 EST
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@xxxxxxxxxxx>
>> ---
>> 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