linux-kernel - Re: [PATCH] Prevent out-of-bounds read/write in bcmasp_netfilt_rd and bcmasp_netfilt

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Message-ID: <2023110301-purist-reputable-fab7@gregkh>
Date:   Fri, 3 Nov 2023 13:57:13 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Yuran Pereira <yuran.pereira@...mail.com>
Cc:     davem@...emloft.net, netdev@...r.kernel.org,
        florian.fainelli@...adcom.com, linux-kernel@...r.kernel.org,
        justin.chen@...adcom.com, edumazet@...gle.com,
        bcm-kernel-feedback-list@...adcom.com, kuba@...nel.org,
        pabeni@...hat.com, linux-kernel-mentees@...ts.linuxfoundation.org
Subject: Re: [PATCH] Prevent out-of-bounds read/write in bcmasp_netfilt_rd
 and bcmasp_netfilt_wr

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@...mail.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