linux-kernel - Re: [Intel-wired-lan] [PATCH net] ice: copy last block omitted in ice_get_module

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Message-ID: <32fdf39c-9772-61a1-e0d7-40a564f640a2@intel.com>
Date:   Wed, 1 Mar 2023 16:13:40 +0100
From:   Alexander Lobakin <aleksander.lobakin@...el.com>
To:     Petr Oros <poros@...hat.com>
CC:     <netdev@...r.kernel.org>, <intel-wired-lan@...ts.osuosl.org>,
        <jesse.brandeburg@...el.com>, <linux-kernel@...r.kernel.org>,
        <edumazet@...gle.com>, <anthony.l.nguyen@...el.com>,
        <kuba@...nel.org>, <pabeni@...hat.com>, <davem@...emloft.net>
Subject: Re: [Intel-wired-lan] [PATCH net] ice: copy last block omitted in
 ice_get_module_eeprom()

From: Petr Oros <poros@...hat.com>
Date: Tue, 28 Feb 2023 21:41:39 +0100

> ice_get_module_eeprom() is broken since commit e9c9692c8a81 ("ice:
> Reimplement module reads used by ethtool") In this refactor,
> ice_get_module_eeprom() reads the eeprom in blocks of size 8.
> But the condition that should protect the buffer overflow
> ignores the last block. The last block always contains zeros.
> Fix adding memcpy for last block.

[...]

> diff --git a/drivers/net/ethernet/intel/ice/ice_ethtool.c b/drivers/net/ethernet/intel/ice/ice_ethtool.c
> index b360bd8f15998b..33b2bee5cfb40f 100644
> --- a/drivers/net/ethernet/intel/ice/ice_ethtool.c
> +++ b/drivers/net/ethernet/intel/ice/ice_ethtool.c
> @@ -4356,6 +4356,8 @@ ice_get_module_eeprom(struct net_device *netdev,
>  			/* Make sure we have enough room for the new block */
>  			if ((i + SFF_READ_BLOCK_SIZE) < ee->len)
>  				memcpy(data + i, value, SFF_READ_BLOCK_SIZE);
> +			else if (ee->len - i > 0)
> +				memcpy(data + i, value, ee->len - i);

Maybe just unify those two?

			copy_len = min_t(u32, SFF_READ_BLOCK_SIZE,
					 ee->len - i);
			memcpy(data + i, value, copy_len);

That's pretty much a reword of your code.
The functional change is good to me.

>  		}
>  	}
>  	return 0;

Thanks,
Olek