When ice_adapter_new() fails, the reserved XArray entry created by
xa_insert() is not released. This causes subsequent insertions at
the same index to return -EBUSY, potentially leading to
NULL pointer dereferences.

Release the reserved entry with xa_release() when adapter allocation
fails to prevent this issue.

Fixes: 0f0023c649c7 ("ice: do not init struct ice_adapter more times than needed")
Suggested-by: Jacob Keller <jacob.e.keller@intel.com>
Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>

---
Changes in v2:
  - Instead of checking the return value of xa_store(), fix the real bug
    where a failed ice_adapter_new() would leave a stale entry in the
    XArray.
  - Use xa_release() to clean up the reserved entry, as suggested by
    Jacob Keller.
---
 drivers/net/ethernet/intel/ice/ice_adapter.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ice/ice_adapter.c b/drivers/net/ethernet/intel/ice/ice_adapter.c
index b53561c34708..9eb100b11439 100644
--- a/drivers/net/ethernet/intel/ice/ice_adapter.c
+++ b/drivers/net/ethernet/intel/ice/ice_adapter.c
@@ -110,8 +110,10 @@ struct ice_adapter *ice_adapter_get(struct pci_dev *pdev)
 			return ERR_PTR(err);
 
 		adapter = ice_adapter_new(pdev);
-		if (!adapter)
+		if (!adapter) {
+			xa_release(&ice_adapters, index);
 			return ERR_PTR(-ENOMEM);
+		}
 		xa_store(&ice_adapters, index, adapter, GFP_KERNEL);
 	}
 	return adapter;
-- 
2.50.1.windows.1

On 9/30/25 03:51, Haotian Zhang wrote:
> When ice_adapter_new() fails, the reserved XArray entry created by
> xa_insert() is not released. This causes subsequent insertions at
> the same index to return -EBUSY, potentially leading to
> NULL pointer dereferences.
> 
> Release the reserved entry with xa_release() when adapter allocation
> fails to prevent this issue.
> 
> Fixes: 0f0023c649c7 ("ice: do not init struct ice_adapter more times than needed")
> Suggested-by: Jacob Keller <jacob.e.keller@intel.com>
> Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
> 
> ---
> Changes in v2:
>    - Instead of checking the return value of xa_store(), fix the real bug
>      where a failed ice_adapter_new() would leave a stale entry in the
>      XArray.
>    - Use xa_release() to clean up the reserved entry, as suggested by
>      Jacob Keller.

this is a correct improvement, but please let me propose other options,
with 2. being my favorite:

1. (just ice changes)
change the call order to be:
(note that it is under a mutex)
xa_load() // return early if another adapter exists
xa_reserve() // return early if no mem
ice_adapter_new() // return early if err
xa_store()


2. (xarray changes)
(perhaps I'm biased as the one introducing the error on error path):
change xa_insert() to return 0 or -EEXIST when used as a reserving call
(IOW: caller wanted to reserve, entry is reserved, so return should be 0
(or -EEXIST if we really want to differentiate in the callers)).


> ---
>   drivers/net/ethernet/intel/ice/ice_adapter.c | 4 +++-
>   1 file changed, 3 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/ice_adapter.c b/drivers/net/ethernet/intel/ice/ice_adapter.c
> index b53561c34708..9eb100b11439 100644
> --- a/drivers/net/ethernet/intel/ice/ice_adapter.c
> +++ b/drivers/net/ethernet/intel/ice/ice_adapter.c
> @@ -110,8 +110,10 @@ struct ice_adapter *ice_adapter_get(struct pci_dev *pdev)
>   			return ERR_PTR(err);
>   
>   		adapter = ice_adapter_new(pdev);
> -		if (!adapter)
> +		if (!adapter) {
> +			xa_release(&ice_adapters, index);
>   			return ERR_PTR(-ENOMEM);
> +		}
>   		xa_store(&ice_adapters, index, adapter, GFP_KERNEL);
>   	}
>   	return adapter;

On 9/30/2025 10:29 PM, Przemek Kitszel wrote:
> On 9/30/25 03:51, Haotian Zhang wrote:
>> When ice_adapter_new() fails, the reserved XArray entry created by
>> xa_insert() is not released. This causes subsequent insertions at
>> the same index to return -EBUSY, potentially leading to
>> NULL pointer dereferences.
>>
>> Release the reserved entry with xa_release() when adapter allocation
>> fails to prevent this issue.
>>
>> Fixes: 0f0023c649c7 ("ice: do not init struct ice_adapter more times than needed")
>> Suggested-by: Jacob Keller <jacob.e.keller@intel.com>
>> Signed-off-by: Haotian Zhang <vulab@iscas.ac.cn>
>>
>> ---
>> Changes in v2:
>>    - Instead of checking the return value of xa_store(), fix the real bug
>>      where a failed ice_adapter_new() would leave a stale entry in the
>>      XArray.
>>    - Use xa_release() to clean up the reserved entry, as suggested by
>>      Jacob Keller.
> 
> this is a correct improvement, but please let me propose other options,
> with 2. being my favorite:
> 
> 1. (just ice changes)
> change the call order to be:
> (note that it is under a mutex)
> xa_load() // return early if another adapter exists
> xa_reserve() // return early if no mem
> ice_adapter_new() // return early if err

You still have to xa_release() here if we return early, but adding the
call to xa_reserve might be more expressive of the intended behavior vs
using xa_insert was.

> xa_store()
> 
> 
> 2. (xarray changes)
> (perhaps I'm biased as the one introducing the error on error path):
> change xa_insert() to return 0 or -EEXIST when used as a reserving call
> (IOW: caller wanted to reserve, entry is reserved, so return should be 0
> (or -EEXIST if we really want to differentiate in the callers)).
> 

If we go this route, I think -EEXIST is the right answer, as it should
only return 0 if *this* call reserved the entry. -EEXIST instead of
-EBUSY could differentiate between "slot is reserved" and "slot is
filled" though.

That would let us fix the issue by having xa_insert differentiate and go
ahead if it fines a reserved entry that was unused. Thats safe for *our*
use case because we know we were under lock and the only way we'd have a
stale reserved entry is if we failed to release it...

I am not certain how other users or maintainer of xarray would feel
about such a change, which makes me think the ice side change is the
best at least initially.

> 
>> ---
>>   drivers/net/ethernet/intel/ice/ice_adapter.c | 4 +++-
>>   1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/intel/ice/ice_adapter.c b/drivers/net/ethernet/intel/ice/ice_adapter.c
>> index b53561c34708..9eb100b11439 100644
>> --- a/drivers/net/ethernet/intel/ice/ice_adapter.c
>> +++ b/drivers/net/ethernet/intel/ice/ice_adapter.c
>> @@ -110,8 +110,10 @@ struct ice_adapter *ice_adapter_get(struct pci_dev *pdev)
>>   			return ERR_PTR(err);
>>   
>>   		adapter = ice_adapter_new(pdev);
>> -		if (!adapter)
>> +		if (!adapter) {
>> +			xa_release(&ice_adapters, index);
>>   			return ERR_PTR(-ENOMEM);
>> +		}
>>   		xa_store(&ice_adapters, index, adapter, GFP_KERNEL);
>>   	}
>>   	return adapter;
>