ice: allow reading the last byte of the NVM and Shadow RAM regions

[PATCH iwl-net] ice: allow reading the last byte of the NVM and Shadow RAM regions

Posted by Petr Oros 1 month, 1 week ago

ice_devlink_nvm_read() rejects a read whose end lands exactly on the
region size, so feeding back the size devlink itself reports fails:

  devlink region show pci/0000:04:00.0/nvm-flash
  pci/0000:04:00.0/nvm-flash: size 10485760 snapshot [] max 1

  devlink region read pci/0000:04:00.0/nvm-flash address 0 length 10485760
  Error: ice: Cannot read beyond the region size.

shadow-ram behaves the same. The regions are created with those sizes, so
a read ending on the size is the whole region and has to be allowed.
ice_read_flat_nvm() uses > for its own Shadow RAM check, and so does
ixgbe, which grew its region support from this code.

Fixes: 3af4b40b0f2f ("ice: implement direct read for NVM and Shadow RAM regions")
Signed-off-by: Petr Oros <poros@redhat.com>
---
 drivers/net/ethernet/intel/ice/devlink/devlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/intel/ice/devlink/devlink.c b/drivers/net/ethernet/intel/ice/devlink/devlink.c
index 8c2b63eef82bd5..a52b6044288975 100644
--- a/drivers/net/ethernet/intel/ice/devlink/devlink.c
+++ b/drivers/net/ethernet/intel/ice/devlink/devlink.c
@@ -1953,7 +1953,7 @@ static int ice_devlink_nvm_read(struct devlink *devlink,
 		return -EOPNOTSUPP;
 	}
 
-	if (offset + size >= nvm_size) {
+	if (offset + size > nvm_size) {
 		NL_SET_ERR_MSG_MOD(extack, "Cannot read beyond the region size");
 		return -ERANGE;
 	}
-- 
2.54.0

Re: [PATCH iwl-net] ice: allow reading the last byte of the NVM and Shadow RAM regions

Posted by Przemek Kitszel 1 month, 1 week ago

On 8/19/26 10:24, Petr Oros wrote:
> ice_devlink_nvm_read() rejects a read whose end lands exactly on the
> region size, so feeding back the size devlink itself reports fails:
> 
>    devlink region show pci/0000:04:00.0/nvm-flash
>    pci/0000:04:00.0/nvm-flash: size 10485760 snapshot [] max 1
> 
>    devlink region read pci/0000:04:00.0/nvm-flash address 0 length 10485760
>    Error: ice: Cannot read beyond the region size.
> 
> shadow-ram behaves the same. The regions are created with those sizes, so
> a read ending on the size is the whole region and has to be allowed.
> ice_read_flat_nvm() uses > for its own Shadow RAM check, and so does
> ixgbe, which grew its region support from this code.
> 
> Fixes: 3af4b40b0f2f ("ice: implement direct read for NVM and Shadow RAM regions")
> Signed-off-by: Petr Oros <poros@redhat.com>
> ---
>   drivers/net/ethernet/intel/ice/devlink/devlink.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/ice/devlink/devlink.c b/drivers/net/ethernet/intel/ice/devlink/devlink.c
> index 8c2b63eef82bd5..a52b6044288975 100644
> --- a/drivers/net/ethernet/intel/ice/devlink/devlink.c
> +++ b/drivers/net/ethernet/intel/ice/devlink/devlink.c
> @@ -1953,7 +1953,7 @@ static int ice_devlink_nvm_read(struct devlink *devlink,
>   		return -EOPNOTSUPP;
>   	}
>   
> -	if (offset + size >= nvm_size) {
> +	if (offset + size > nvm_size) {
>   		NL_SET_ERR_MSG_MOD(extack, "Cannot read beyond the region size");
>   		return -ERANGE;
>   	}

Thank you,
Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>

Re: [PATCH iwl-net] ice: allow reading the last byte of the NVM and Shadow RAM regions

Posted by Jacob Keller 1 month, 1 week ago

On 8/19/2026 3:54 AM, Przemek Kitszel wrote:
> On 8/19/26 10:24, Petr Oros wrote:
>> ice_devlink_nvm_read() rejects a read whose end lands exactly on the
>> region size, so feeding back the size devlink itself reports fails:
>>
>>    devlink region show pci/0000:04:00.0/nvm-flash
>>    pci/0000:04:00.0/nvm-flash: size 10485760 snapshot [] max 1
>>
>>    devlink region read pci/0000:04:00.0/nvm-flash address 0 length
>> 10485760
>>    Error: ice: Cannot read beyond the region size.
>>
>> shadow-ram behaves the same. The regions are created with those sizes, so
>> a read ending on the size is the whole region and has to be allowed.
>> ice_read_flat_nvm() uses > for its own Shadow RAM check, and so does
>> ixgbe, which grew its region support from this code.
>>
>> Fixes: 3af4b40b0f2f ("ice: implement direct read for NVM and Shadow
>> RAM regions")
>> Signed-off-by: Petr Oros <poros@redhat.com>
>> ---
>>   drivers/net/ethernet/intel/ice/devlink/devlink.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/ethernet/intel/ice/devlink/devlink.c b/
>> drivers/net/ethernet/intel/ice/devlink/devlink.c
>> index 8c2b63eef82bd5..a52b6044288975 100644
>> --- a/drivers/net/ethernet/intel/ice/devlink/devlink.c
>> +++ b/drivers/net/ethernet/intel/ice/devlink/devlink.c
>> @@ -1953,7 +1953,7 @@ static int ice_devlink_nvm_read(struct devlink
>> *devlink,
>>           return -EOPNOTSUPP;
>>       }
>>   -    if (offset + size >= nvm_size) {
>> +    if (offset + size > nvm_size) {
>>           NL_SET_ERR_MSG_MOD(extack, "Cannot read beyond the region
>> size");
>>           return -ERANGE;
>>       }
> 
> Thank you,
> Reviewed-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>

Oops! Thanks for fixing my off-by-one error.

Acked-by: Jacob Keller <jacob.e.keller@intel.com>

Thanks,
Jake