linux-kernel - Re: [PATCH 4.4 19/47] igb: Check if num of q_vectors is smaller than max before array access

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Message-ID: <20210726215744.GA4797@amd>
Date:   Mon, 26 Jul 2021 23:57:44 +0200
From:   Pavel Machek <pavel@...x.de>
To:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Aleksandr Loktionov <aleksandr.loktionov@...el.com>,
        Grzegorz Siwik <grzegorz.siwik@...el.com>,
        Arkadiusz Kubalewski <arkadiusz.kubalewski@...el.com>,
        Slawomir Laba <slawomirx.laba@...el.com>,
        Sylwester Dziedziuch <sylwesterx.dziedziuch@...el.com>,
        Mateusz Palczewski <mateusz.placzewski@...el.com>,
        Tony Brelinski <tonyx.brelinski@...el.com>,
        Tony Nguyen <anthony.l.nguyen@...el.com>,
        Sasha Levin <sashal@...nel.org>
Subject: Re: [PATCH 4.4 19/47] igb: Check if num of q_vectors is smaller than
 max before array access

Hi!

> [ Upstream commit 6c19d772618fea40d9681f259368f284a330fd90 ]
> 
> Ensure that the adapter->q_vector[MAX_Q_VECTORS] array isn't accessed
> beyond its size. It was fixed by using a local variable num_q_vectors
> as a limit for loop index, and ensure that num_q_vectors is not bigger
> than MAX_Q_VECTORS.

Ok, so this is interesting design.

> +++ b/drivers/net/ethernet/intel/igb/igb_main.c
> @@ -945,6 +945,7 @@ static void igb_configure_msix(struct igb_adapter *adapter)
>   **/
>  static int igb_request_msix(struct igb_adapter *adapter)
>  {
> +	unsigned int num_q_vectors = adapter->num_q_vectors;
>  	struct net_device *netdev = adapter->netdev;
>  	int i, err = 0, vector = 0, free_vector = 0;
>  
> @@ -953,7 +954,13 @@ static int igb_request_msix(struct igb_adapter *adapter)
>  	if (err)
>  		goto err_out;
>  
> -	for (i = 0; i < adapter->num_q_vectors; i++) {
> +	if (num_q_vectors > MAX_Q_VECTORS) {
> +		num_q_vectors = MAX_Q_VECTORS;
> +		dev_warn(&adapter->pdev->dev,
> +			 "The number of queue vectors (%d) is higher than max allowed (%d)\n",
> +			 adapter->num_q_vectors, MAX_Q_VECTORS);
> +	}
> +	for (i = 0; i < num_q_vectors; i++) {
>  		struct igb_q_vector *q_vector = adapter->q_vector[i];
>  
>  		vector++;

We limit num_q_vectors here, but too big value remains in
adapter->num_q_vectors. Loop in igb_request_msix is fixed, but there's
similar loop in igb_configure_msix() and in igb_free_irq() and
igp_up() and ...

Either adapter->num_q_vectors should be limited, or all those places
need fixing, no?

Best regards,
								Pavel
-- 
DENX Software Engineering GmbH,      Managing Director: Wolfgang Denk
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

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