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From:   Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
To:     coverity-bot <keescook@chromium.org>
CC:     Jakub Kicinski <kuba@kernel.org>, Paolo Abeni <pabeni@redhat.com>,
        Richard Cochran <richardcochran@gmail.com>,
        Russell King <linux@armlinux.org.uk>,
        Andrew Lunn <andrew@lunn.ch>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        "netdev@vger.kernel.org" <netdev@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Sergey Shtylyov <s.shtylyov@omp.ru>,
        "linux-renesas-soc@vger.kernel.org" 
        <linux-renesas-soc@vger.kernel.org>,
        "Gustavo A. R. Silva" <gustavo@embeddedor.com>,
        "linux-next@vger.kernel.org" <linux-next@vger.kernel.org>,
        "linux-hardening@vger.kernel.org" <linux-hardening@vger.kernel.org>
Subject: RE: Coverity: rswitch_gwca_queue_alloc_skb(): Control flow issues
Thread-Topic: Coverity: rswitch_gwca_queue_alloc_skb(): Control flow issues
Thread-Index: AQHY8IPHt28QOrskV0CLeS7WksgRGK4ysbyg
Date:   Mon, 7 Nov 2022 01:38:33 +0000
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References: <202211041229.F3B37C03@keescook>
In-Reply-To: <202211041229.F3B37C03@keescook>
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Hello!

> From: coverity-bot, Sent: Saturday, November 5, 2022 4:30 AM
>=20
> Hello!
>=20
> This is an experimental semi-automated report about issues detected by
> Coverity from a scan of next-20221104 as part of the linux-next scan proj=
ect:
<snip>
>=20
> You're getting this email because you were associated with the identified
> lines of code (noted below) that were touched by commits:
>=20
>   Wed Nov 2 12:38:53 2022 +0000
>     3590918b5d07 ("net: ethernet: renesas: Add support for "Ethernet Swit=
ch"")
>=20
> Coverity reported the following:
>=20
> *** CID 1527147:  Control flow issues  (NO_EFFECT)
> drivers/net/ethernet/renesas/rswitch.c:270 in rswitch_gwca_queue_alloc_sk=
b()
> 264     			goto err;
> 265     	}
> 266
> 267     	return 0;
> 268
> 269     err:
> vvv     CID 1527147:  Control flow issues  (NO_EFFECT)
> vvv     This greater-than-or-equal-to-zero comparison of an unsigned valu=
e is always true. "i >=3D 0U".
> 270     	for (i--; i >=3D 0; i--) {
> 271     		index =3D (i + start_index) % gq->ring_size;
> 272     		dev_kfree_skb(gq->skbs[index]);
> 273     		gq->skbs[index] =3D NULL;
> 274     	}
> 275
>=20
> If this is a false positive, please let us know so we can mark it as
> such, or teach the Coverity rules to be smarter. If not, please make
> sure fixes get into linux-next. :) For patches fixing this, please
> include these lines (but double-check the "Fixes" first):

Thank you for the report! I should fix the driver.=20
I also realized that rswitch_gwca_queue_ts_fill() has the same issue.

Best regards,
Yoshihiro Shimoda

> Reported-by: coverity-bot <keescook+coverity-bot@chromium.org>
> Addresses-Coverity-ID: 1527147 ("Control flow issues")
> Fixes: 3590918b5d07 ("net: ethernet: renesas: Add support for "Ethernet S=
witch"")
>=20
> Thanks for your attention!
>=20
> --
> Coverity-bot