linux-kernel - Re: [PATCH] e1000: fix OOB in e1000_tbi_should

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Message-ID: <b53c3a7e-6833-4e87-ae24-c344f2c3c5a1@intel.com>
Date: Mon, 17 Nov 2025 15:24:05 -0800
From: Tony Nguyen <anthony.l.nguyen@...el.com>
To: Guangshuo Li <lgs201920130244@...il.com>, "David S. Miller"
	<davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni
	<pabeni@...hat.com>, Florian Westphal <fw@...len.de>,
	<intel-wired-lan@...ts.osuosl.org>, <netdev@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>
CC: <stable@...r.kernel.org>
Subject: Re: [PATCH] e1000: fix OOB in e1000_tbi_should_accept()



On 11/4/2025 12:28 AM, Guangshuo Li wrote:
> In e1000_tbi_should_accept() we read the last byte of the frame via
> 'data[length - 1]' to evaluate the TBI workaround. If the descriptor-
> reported length is zero or larger than the actual RX buffer size, this
> read goes out of bounds and can hit unrelated slab objects. The issue
> is observed from the NAPI receive path (e1000_clean_rx_irq):

...

> --- a/drivers/net/ethernet/intel/e1000/e1000_main.c
> +++ b/drivers/net/ethernet/intel/e1000/e1000_main.c
> @@ -4090,6 +4090,12 @@ static bool e1000_tbi_should_accept(struct e1000_adapter *adapter,
>   				    u8 status, u8 errors,
>   				    u32 length, const u8 *data)
>   {
> +	/* Guard against OOB on data[length - 1] */
> +	if (unlikely(!length))
> +		return false;
> +	/* Upper bound: length must not exceed rx_buffer_len */
> +	if (unlikely(length > adapter->rx_buffer_len))
> +		return false;

The change itself looks fine, however, the declarations should be at the 
beginning of the function so this should be moved to be after that.

>   	struct e1000_hw *hw = &adapter->hw;
>   	u8 last_byte = *(data + length - 1);

Also, since last_byte uses length, this should be broken up and the 
assignment moved after the added checks.

Thanks,
Tony