Re: [PATCH v2 1/1] e1000e: fix heap overflow in e1000_set_eeprom()

[Tony Nguyen <anthony.l.nguyen@intel.com>]

On 5/27/2025 1:56 AM, Mikael Wessel wrote:
> The ETHTOOL_SETEEPROM ioctl copies user data into a kmalloc'ed buffer
> without validating eeprom->len and eeprom->offset.  A CAP_NET_ADMIN
> user can overflow the heap and crash the kernel or gain code execution.
> 
> Validate length and offset before memcpy().
> 
> Fixes: bc7f75fa9788 ("[E1000E]: New pci-express e1000 driver (currently for ICH9 devices only)")
> Reported-by: Mikael Wessel <post@mikaelkw.online>
> Signed-off-by: Mikael Wessel <post@mikaelkw.online>
> Cc: stable@vger.kernel.org
> ---
>   drivers/net/ethernet/intel/e1000e/ethtool.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/net/ethernet/intel/e1000e/ethtool.c b/drivers/net/ethernet/intel/e1000e/ethtool.c
> index 9364bc2b4eb1..98e541e39730 100644
> --- a/drivers/net/ethernet/intel/e1000e/ethtool.c
> +++ b/drivers/net/ethernet/intel/e1000e/ethtool.c
> @@ -596,6 +596,9 @@ static int e1000_set_eeprom(struct net_device *netdev,
>   	for (i = 0; i < last_word - first_word + 1; i++)
>   		le16_to_cpus(&eeprom_buff[i]);
>   
> +        if (eeprom->len > max_len ||
> +            eeprom->offset > max_len - eeprom->len)
> +                return -EINVAL;

This is going to cause 'eeprom_buff' to leak. You should use the goto 
out, however, seems like these checks can be moved up before the 
allocation is done. Also, indentation looks off.

Thanks,
Tony

>   	memcpy(ptr, bytes, eeprom->len);
>   
>   	for (i = 0; i < last_word - first_word + 1; i++)