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Date:   Fri, 3 Nov 2023 13:57:13 +0100
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Yuran Pereira <yuran.pereira@hotmail.com>
Cc:     davem@davemloft.net, netdev@vger.kernel.org,
        florian.fainelli@broadcom.com, linux-kernel@vger.kernel.org,
        justin.chen@broadcom.com, edumazet@google.com,
        bcm-kernel-feedback-list@broadcom.com, kuba@kernel.org,
        pabeni@redhat.com, linux-kernel-mentees@lists.linuxfoundation.org
Subject: Re: [PATCH] Prevent out-of-bounds read/write in bcmasp_netfilt_rd
 and bcmasp_netfilt_wr
Message-ID: <2023110301-purist-reputable-fab7@gregkh>
References: <DB3PR10MB6835E073F668AD24F57AE64AE8A5A@DB3PR10MB6835.EURPRD10.PROD.OUTLOOK.COM>
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On Fri, Nov 03, 2023 at 05:57:48PM +0530, Yuran Pereira wrote:
> The functions `bcmasp_netfilt_rd` and `bcmasp_netfilt_wr` both call
> `bcmasp_netfilt_get_reg_offset` which, when it fails, returns `-EINVAL`.
> This could lead to an out-of-bounds read or write when `rx_filter_core_rl`
> or `rx_filter_core_wl` is called.
> 
> This patch adds a check in both functions to return immediately if
> `bcmasp_netfilt_get_reg_offset` fails. This prevents potential out-of-bounds read
> or writes, and ensures that no undefined or buggy behavior would originate from
> the failure of `bcmasp_netfilt_get_reg_offset`.
> 
> Addresses-Coverity-IDs: 1544536 ("Out-of-bounds access")
> Signed-off-by: Yuran Pereira <yuran.pereira@hotmail.com>
> ---
>  drivers/net/ethernet/broadcom/asp2/bcmasp.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/net/ethernet/broadcom/asp2/bcmasp.c b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
> index 29b04a274d07..8b90b761bdec 100644
> --- a/drivers/net/ethernet/broadcom/asp2/bcmasp.c
> +++ b/drivers/net/ethernet/broadcom/asp2/bcmasp.c
> @@ -227,6 +227,8 @@ static void bcmasp_netfilt_wr(struct bcmasp_priv *priv,
>  
>  	reg_offset = bcmasp_netfilt_get_reg_offset(priv, nfilt, reg_type,
>  						   offset);
> +	if (reg_offset < 0)
> +		return;
>  
>  	rx_filter_core_wl(priv, val, reg_offset);
>  }
> @@ -244,6 +246,8 @@ static u32 bcmasp_netfilt_rd(struct bcmasp_priv *priv,
>  
>  	reg_offset = bcmasp_netfilt_get_reg_offset(priv, nfilt, reg_type,
>  						   offset);
> +	if (reg_offset < 0)
> +		return 0;

Shouldn't you return an error here?

thanks

greg k-h