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Fri, 04 Sep 2026 03:57:10 -0700 (PDT) Date: Fri, 4 Sep 2026 12:57:09 +0200 From: Lorenzo Bianconi To: ZhaoJinming Cc: Maxime Chevallier , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Maxime Coquelin , Alexandre Torgue , Simon Horman , Christian Marangi , Jose Abreu , netdev@vger.kernel.org, linux-stm32@st-md-mailman.stormreply.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] net: stmmac: clear dma_conf in __stmmac_open error path Message-ID: References: <20260904-fix-stmmac-mtu-change-use-after-free-v2-1-91e680476921@uniontech.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="E1MazB2LUUx/XJQ2" Content-Disposition: inline In-Reply-To: <20260904-fix-stmmac-mtu-change-use-after-free-v2-1-91e680476921@uniontech.com> X-Proofpoint-Spam-Info: AW1haW4tMjYwOTA0MDA5OCBTYWx0ZWRfX09VosEj2T3/s 1al+vEhatFeBEcMmrwa3mmf1Knz518ArA/eTTU/B9gdSubLM6dlR83HTlvG1aKt6OcL3IBFmAwZ CESr1Y8cp0XJtzz4ej5+GvyoANS+K7g= X-Proofpoint-ORIG-GUID: BrW7lOZOSwFztAjIBPv93XL7C-stO4y4 X-Proofpoint-GUID: BrW7lOZOSwFztAjIBPv93XL7C-stO4y4 X-Authority-Analysis: v=2.4 cv=T/S8ifKQ c=1 sm=1 tr=0 ts=6a9aa40b cx=c_pps a=hnmNkyzTK/kJ09Xio7VxxA==:117 a=WpTaRW6qxYHRGzLzQsVYzg==:17 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=_glEPmIy2e8OvE2BGh3C:22 a=VwQbUJbxAAAA:8 a=iHwBjlyiAAAA:8 a=SaV9t1am_M5Vh_LyuNUA:9 a=CjuIK1q_8ugA:10 a=sX82_v1_a9lhBkuKYFsA:9 a=PEH46H7Ffwr30OY-TuGO:22 a=uNSKXYNwxGiU6LD0JREI:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTA0MDA5OCBTYWx0ZWRfX1sYddCX8m/7N YAdHr7yC2umy5r9CZyvuivr9cmhJlSxtu4KDhUaH9CVLdsIvUdeBbbPZR57RIzeyVCMqJ8TD8Yw eGP1Q0bSoQOf5XyY4Ulp/1h9/BDglWLE2fs2BNwrgJdy55mfhkVgP+FQj8We+1oi9SYRaR9Jnri 3xIAEKVmjL5UkQ4zFNn3Ay9T4bZ+geEp00kG5X3tynnQFbsQ4+h8E4xfSMaoW5+aWvZDEYCCL2R gWTnJRP5zfokiJSNWQcb4XHh8L7acXI9F1+aJEopI1STcUkTVV1UUNQvzui6vRJ6Lib7zv4pzFa 8BKt6PPm8Km2aMUkjETQiU5mB11Qx3PyDtnqQi8JBCZaQaw54o0dLwS7inbsZDFZubwUgvCzJqQ eu1ISVFjwdLBGTcDFNJHZzR4pY5LE2zCGUd9EW0trgrid2xK6i6AES/9Uw5S+sJF/xlIvKv7zys JLPUq4scptrTXUcVBLQ== X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1176,Hydra:6.1.134,FMLib:17.12.100.49 definitions=2026-09-04_03,2026-09-03_01,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 phishscore=0 lowpriorityscore=0 impostorscore=0 priorityscore=1501 malwarescore=0 clxscore=1015 spamscore=0 suspectscore=0 adultscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2606150000 definitions=main-2609040098 --E1MazB2LUUx/XJQ2 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > __stmmac_open() copies the freshly allocated dma_conf into priv->dma_conf > via memcpy() before it can fail, e.g. in stmmac_request_irq(). When it > does fail, the callers free the dma_conf descriptor resources and the > struct itself, but priv->dma_conf still holds pointers to those freed > resources, a use-after-free that triggers when a subsequent > stmmac_release() or another MTU change releases the resources again. >=20 > Undo the memcpy in the error path by zeroing priv->dma_conf, leaving the > state consistent regardless of the caller. >=20 > Fixes: 30134b7c47bd2 ("net: ethernet: stmicro: stmmac: fix possible memor= y leak in __stmmac_open") > Signed-off-by: ZhaoJinming Hi ZhaoJinming, I agree the issue is real, but assuming free_dma_desc_resources() always tolerates a fully zeroed dma_conf struct seems a bit fragile to me. Is it better to use a pointer for priv->dma_conf that we can set to NULL in case of error? What do you think? Regards, Lorenzo > --- > Changes in v2: > - Move the clearing of priv->dma_conf from stmmac_change_mtu() into > __stmmac_open() error path, undoing the memcpy() at the point where it > was made and covering both callers. > - Link to v1: https://lore.kernel.org/r/20260903-fix-stmmac-mtu-change-us= e-after-free-v1-1-c81dc7d6d18a@uniontech.com > --- > drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 1 + > 1 file changed, 1 insertion(+) >=20 > diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/= net/ethernet/stmicro/stmmac/stmmac_main.c > index 24656b35350b14454fb10deced6516eb89e2c0c9..4369e64faf9f878aa20ac5075= 705044f55c5f8bf 100644 > --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c > @@ -4190,6 +4190,7 @@ static int __stmmac_open(struct net_device *dev, > =20 > stmmac_release_ptp(priv); > init_error: > + memset(&priv->dma_conf, 0, sizeof(priv->dma_conf)); > return ret; > } > =20 >=20 > --- > base-commit: a500db7819c50db59e55f1b4fa1c3baa5a2616f3 > change-id: 20260903-fix-stmmac-mtu-change-use-after-free-693da6eb4a30 >=20 > Best regards, > --=20 > ZhaoJinming >=20 >=20 --E1MazB2LUUx/XJQ2 Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQTquNwa3Txd3rGGn7Y6cBh0uS2trAUCapqkBQAKCRA6cBh0uS2t rM/dAQDZOoJDs5HeJVYmNfdj9lanQiEx9EXr1USvD3sf/UejtAD+KxxYvB/7Bsu/ 1P09VTIKMhSBbGLdyJNvqrrQNHSSOQc= =8C6m -----END PGP SIGNATURE----- --E1MazB2LUUx/XJQ2--