netdev - Re: [PATCH 2/2 net-next] thunderbolt: Right shifting to zero bug in tbnet_handle

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Date:   Tue, 17 Oct 2017 13:17:30 +0000
From:   "Bernat, Yehezkel" <yehezkel.bernat@...el.com>
To:     "dan.carpenter@...cle.com" <dan.carpenter@...cle.com>,
        "Jamet, Michael" <michael.jamet@...el.com>,
        "Levy, Amir (Jer)" <amir.jer.levy@...el.com>
CC:     "mika.westerberg@...ux.intel.com" <mika.westerberg@...ux.intel.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "davem@...emloft.net" <davem@...emloft.net>,
        "kernel-janitors@...r.kernel.org" <kernel-janitors@...r.kernel.org>
Subject: Re: [PATCH 2/2 net-next] thunderbolt: Right shifting to zero bug in
 tbnet_handle_packet()

On Tue, 2017-10-17 at 15:33 +0300, Dan Carpenter wrote:
> There is a problem when we do:
> 
> 	sequence = pkg->hdr.length_sn & TBIP_HDR_SN_MASK;
> 	sequence >>= TBIP_HDR_SN_SHIFT;
> 
> TBIP_HDR_SN_SHIFT is 27, and right shifting a u8 27 bits is always
> going to result in zero.  The fix is to declare these variables as
> u32.
> 
> Fixes: e69b6c02b4c3 ("net: Add support for networking over
> Thunderbolt cable")
> Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
> 
> diff --git a/drivers/net/thunderbolt.c b/drivers/net/thunderbolt.c
> index 1a7bc0bf4598..435854688a7a 100644
> --- a/drivers/net/thunderbolt.c
> +++ b/drivers/net/thunderbolt.c
> @@ -394,7 +394,7 @@ static int tbnet_handle_packet(const void *buf,
> size_t size, void *data)
>  	struct tbnet *net = data;
>  	u32 command_id;
>  	int ret = 0;
> -	u8 sequence;
> +	u32 sequence;
>  	u64 route;
>  
>  	/* Make sure the packet is for us */

Acked-by: Yehezkel Bernat <yehezkel.bernat@...el.com>

Thanks!