netdev - Re: [PATCH net-next] net: dsa: microchip: Uninitialized variable in ksz9477_acl_move

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Message-ID: <20231006104550.GB3112038@pengutronix.de>
Date: Fri, 6 Oct 2023 12:45:50 +0200
From: Oleksij Rempel <o.rempel@...gutronix.de>
To: Paolo Abeni <pabeni@...hat.com>
Cc: Vladimir Oltean <olteanv@...il.com>,
	Dan Carpenter <dan.carpenter@...aro.org>,
	Oleksij Rempel <linux@...pel-privat.de>,
	Woojung Huh <woojung.huh@...rochip.com>,
	UNGLinuxDriver@...rochip.com, Andrew Lunn <andrew@...n.ch>,
	Florian Fainelli <f.fainelli@...il.com>,
	"David S. Miller" <davem@...emloft.net>,
	Eric Dumazet <edumazet@...gle.com>,
	Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH net-next] net: dsa: microchip: Uninitialized variable in
 ksz9477_acl_move_entries()

Hi Vladimir, Paolo,

On Thu, Oct 05, 2023 at 10:06:22AM +0200, Paolo Abeni wrote:
> On Mon, 2023-10-02 at 18:28 +0300, Vladimir Oltean wrote:
> > Hi Oleksij,
> > 
> > On Wed, Sep 27, 2023 at 04:46:24PM +0200, Oleksij Rempel wrote:
> > > On Wed, Sep 27, 2023 at 03:53:37PM +0300, Dan Carpenter wrote:
> > > > Smatch complains that if "src_idx" equals "dst_idx" then
> > > > ksz9477_validate_and_get_src_count() doesn't initialized "src_count".
> > > > Set it to zero for this situation.
> > > > 
> > > > Fixes: 002841be134e ("net: dsa: microchip: Add partial ACL support for ksz9477 switches")
> > > > Signed-off-by: Dan Carpenter <dan.carpenter@...aro.org>
> > > 
> > > Reviewed-by: Oleksij Rempel <o.rempel@...gutronix.de>
> > > 
> > > Thank you!
> > > 
> > > > ---
> > > >  drivers/net/dsa/microchip/ksz9477_acl.c | 3 ++-
> > > >  1 file changed, 2 insertions(+), 1 deletion(-)
> > > > 
> > > > diff --git a/drivers/net/dsa/microchip/ksz9477_acl.c b/drivers/net/dsa/microchip/ksz9477_acl.c
> > > > index 06d74c19eb94..e554cd4a024b 100644
> > > > --- a/drivers/net/dsa/microchip/ksz9477_acl.c
> > > > +++ b/drivers/net/dsa/microchip/ksz9477_acl.c
> > > > @@ -554,7 +554,8 @@ static int ksz9477_acl_move_entries(struct ksz_device *dev, int port,
> > > >  	struct ksz9477_acl_entry buffer[KSZ9477_ACL_MAX_ENTRIES];
> > > >  	struct ksz9477_acl_priv *acl = dev->ports[port].acl_priv;
> > > >  	struct ksz9477_acl_entries *acles = &acl->acles;
> > > > -	int src_count, ret, dst_count;
> > > > +	int ret, dst_count;
> > > > +	int src_count = 0;
> > > >  
> > > >  	ret = ksz9477_validate_and_get_src_count(dev, port, src_idx, dst_idx,
> > > >  						 &src_count, &dst_count);
> > > > -- 
> > > > 2.39.2
> > > > 
> > > > 
> > > > 
> > > 
> > > -- 
> > > Pengutronix e.K.                           |                             |
> > > Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
> > > 31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
> > > Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
> > 
> > For the case where src_idx == dst_idx that Dan points out, is this patch
> > sufficient to ensure that ksz9477_acl_move_entries() will not execute
> > unwanted code paths? For example, it will still call ksz9477_move_entries_upwards(),
> > which from what I can tell, will do something given the way in which it's written.
> > 
> > Perhaps it would be better to move this line:
> > 
> > 	/* Nothing to do */
> > 	if (src_idx == dst_idx)
> > 		return 0;
> > 
> > outside of ksz9477_validate_and_get_src_count() and into its single caller,
> > ksz9477_acl_move_entries()?
> 
> Additionally, it looks like that when (src_idx == dst_idx) even
> dst_count is not initialized but is still later used.

Ack, moving if (src_idx == dst_idx) to ksz9477_acl_move_entries() is the
proper fix.

Regards,
Oleksij
-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |