RE: [Intel-wired-lan] [PATCH net-next v2 2/2] e1000e: limit endianness conversion to boundary words

[Loktionov, Aleksandr]

> -----Original Message-----
> From: Intel-wired-lan <intel-wired-lan-bounces@xxxxxxxxxx> On Behalf
> Of Agalakov Daniil
> Sent: Wednesday, March 25, 2026 4:16 PM
> To: Nguyen, Anthony L <anthony.l.nguyen@xxxxxxxxx>
> Cc: Agalakov Daniil <ade@xxxxxxxxx>; Kitszel, Przemyslaw
> <przemyslaw.kitszel@xxxxxxxxx>; Andrew Lunn <andrew+netdev@xxxxxxx>;
> David S. Miller <davem@xxxxxxxxxxxxx>; Eric Dumazet
> <edumazet@xxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; Paolo Abeni
> <pabeni@xxxxxxxxxx>; intel-wired-lan@xxxxxxxxxxxxxxxx;
> netdev@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; lvc-
> project@xxxxxxxxxxxxxxxx; Daniil Iskhakov <dish@xxxxxxxxx>; Roman
> Razov <rrv@xxxxxxxxx>
> Subject: [Intel-wired-lan] [PATCH net-next v2 2/2] e1000e: limit
> endianness conversion to boundary words
> 
> [Why]
> In e1000_set_eeprom(), the eeprom_buff is allocated to hold a range of
> words. However, only the boundary words (the first and the last) are
> populated from the EEPROM if the write request is not word-aligned.
> The words in the middle of the buffer remain uninitialized because
> they are intended to be completely overwritten by the new data via
> memcpy().
> 
> The previous implementation had a loop that performed le16_to_cpus()
> on the entire buffer. This resulted in endianness conversion being
> performed on uninitialized memory for all interior words.
> 
> Fix this by converting the endianness only for the boundary words
> immediately after they are successfully read from the EEPROM.
> 
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
> 
> Co-developed-by: Iskhakov Daniil <dish@xxxxxxxxx>
> Signed-off-by: Iskhakov Daniil <dish@xxxxxxxxx>
> Signed-off-by: Agalakov Daniil <ade@xxxxxxxxx>
> ---
> v2:
>  - Split from the original bugfix series and targeted at 'net-text'.
>  - Removed the Fixes: tag; limiting the conversion scope is an
>    improvement to avoid unnecessary processing of uninitialized
> memory.
>  - Improved commit description for clarity.
>  - Note on e1000e: this driver already contains the necessary return
>    value checks for EEPROM reads, so only the endianness conversion
>    cleanup is included for e1000e.
> 
>  drivers/net/ethernet/intel/e1000e/ethtool.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/ethernet/intel/e1000e/ethtool.c
> b/drivers/net/ethernet/intel/e1000e/ethtool.c
> index dbed30943ef4..785d89477c43 100644
> --- a/drivers/net/ethernet/intel/e1000e/ethtool.c
> +++ b/drivers/net/ethernet/intel/e1000e/ethtool.c
> @@ -583,13 +583,21 @@ static int e1000_set_eeprom(struct net_device
> *netdev,
>  		/* need read/modify/write of first changed EEPROM word
> */
>  		/* only the second byte of the word is being modified */
>  		ret_val = e1000_read_nvm(hw, first_word, 1,
> &eeprom_buff[0]);
> +
> +		/* Device's eeprom is always little-endian, word
> addressable */
> +		le16_to_cpus(&eeprom_buff[0]);
> +
>  		ptr++;
>  	}
> -	if (((eeprom->offset + eeprom->len) & 1) && (!ret_val))
> +	if (((eeprom->offset + eeprom->len) & 1) && (!ret_val)) {
>  		/* need read/modify/write of last changed EEPROM word */
>  		/* only the first byte of the word is being modified */
>  		ret_val = e1000_read_nvm(hw, last_word, 1,
>  					 &eeprom_buff[last_word -
> first_word]);
> +
> +		/* Device's eeprom is always little-endian, word
> addressable */
> +		le16_to_cpus(&eeprom_buff[last_word - first_word]);
> +	}
> 
>  	if (ret_val)
>  		goto out;
> --
> 2.51.0

Reviewed-by: Aleksandr Loktionov <aleksandr.loktionov@xxxxxxxxx>