linux-kernel - Re: [PATCH] bnx2fc: shift wrapping bug in bnx2fc_process_unsol

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Message-ID: <20161128132137.GR6266@mwanda>
Date:   Mon, 28 Nov 2016 16:24:45 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Christophe JAILLET <christophe.jaillet@...adoo.fr>
Cc:     QLogic-Storage-Upstream@...gic.com, jejb@...ux.vnet.ibm.com,
        martin.petersen@...cle.com, linux-scsi@...r.kernel.org,
        linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org
Subject: Re: [PATCH] bnx2fc: shift wrapping bug in
 bnx2fc_process_unsol_compl()

On Sat, Nov 26, 2016 at 07:36:29PM +0100, Christophe JAILLET wrote:
> BNX2FC_NUM_ERR_BITS is 63. err_warn_bit_map is a u64. So, to make sure that
> no shift wrapping will occur, we need need additionnal casting.
> 
> The same test is already done a few lines above and '(u64)1' is already
> used there. So just do the same here.
> 
> Signed-off-by: Christophe JAILLET <christophe.jaillet@...adoo.fr>
> ---
> I guess that this could also be written with a '1ULL << i' which would be
> cleaner and less verbose IMHO, but apparently this driver does not use
> such things yet. So keep the current style with casting.

Ugh...  No.  This is not code to emulate.  Use 1ULL << i.  Even if we
did the cast, you would only need one:

			if (err_warn_bit_map & ((u64)1 << i)) {


regards,
dan carpenter