linux-kernel - Re: [PATCH 1/2] scsi: qedf: Replace kmalloc

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Message-ID: <2025020658-backlog-riot-5faf@gregkh>
Date: Thu, 6 Feb 2025 06:38:21 +0100
From: Greg KH <gregkh@...uxfoundation.org>
To: Jiasheng Jiang <jiashengjiangcool@...il.com>
Cc: markus.elfring@....de, GR-QLogic-Storage-Upstream@...vell.com,
	James.Bottomley@...senpartnership.com, arun.easi@...ium.com,
	bvanassche@....org, jhasan@...vell.com,
	linux-kernel@...r.kernel.org, linux-scsi@...r.kernel.org,
	manish.rangankar@...ium.com, martin.petersen@...cle.com,
	nilesh.javali@...ium.com, skashyap@...vell.com,
	stable@...r.kernel.org
Subject: Re: [PATCH 1/2] scsi: qedf: Replace kmalloc_array() with kcalloc()

On Thu, Feb 06, 2025 at 06:36:58AM +0100, Greg KH wrote:
> On Thu, Feb 06, 2025 at 05:25:22AM +0000, Jiasheng Jiang wrote:
> > Replace kmalloc_array() with kcalloc() to avoid old (dirty) data being
> > used/freed.
> 
> Used/freed where?
> 
> > 
> > Fixes: 61d8658b4a43 ("scsi: qedf: Add QLogic FastLinQ offload FCoE driver framework.")
> > Cc: <stable@...r.kernel.org> # v5.10+
> > Signed-off-by: Jiasheng Jiang <jiashengjiangcool@...il.com>
> > ---
> >  drivers/scsi/qedf/qedf_io.c | 4 +---
> >  1 file changed, 1 insertion(+), 3 deletions(-)
> > 
> > diff --git a/drivers/scsi/qedf/qedf_io.c b/drivers/scsi/qedf/qedf_io.c
> > index fcfc3bed02c6..d52057b97a4f 100644
> > --- a/drivers/scsi/qedf/qedf_io.c
> > +++ b/drivers/scsi/qedf/qedf_io.c
> > @@ -254,9 +254,7 @@ struct qedf_cmd_mgr *qedf_cmd_mgr_alloc(struct qedf_ctx *qedf)
> >  	}
> >  
> >  	/* Allocate pool of io_bdts - one for each qedf_ioreq */
> > -	cmgr->io_bdt_pool = kmalloc_array(num_ios, sizeof(struct io_bdt *),
> > -	    GFP_KERNEL);
> > -
> > +	cmgr->io_bdt_pool = kcalloc(num_ios, sizeof(*cmgr->io_bdt_pool), GFP_KERNEL);
> 
> This is just an array that is then properly all initialized a few lines
> below this.
> 
> So why does this need to be zeroed out at all?

Oh, I think I figured it out, but your text for the changelog is wrong,
and needs to be fixed to properly describe what is going on here.

thanks,

greg k-h