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Thu, 10 Sep 2026 02:22:06 -0700 (PDT) Received: from localhost ([188.216.77.92]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-485883a9b49sm41732270f8f.17.2026.09.10.02.22.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Sep 2026 02:22:05 -0700 (PDT) Date: Thu, 10 Sep 2026 11:22:04 +0200 From: Lorenzo Bianconi To: ZhaoJinming Cc: Maxime Chevallier , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Maxime Coquelin , Alexandre Torgue , 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 net] net: stmmac: fix stale descriptors and DMA mapping leak on Tx map failure Message-ID: References: <20260910-stmmac-fix-vlan-desc-leak-v1-1-6b07dca5e5e8@uniontech.com> Precedence: bulk X-Mailing-List: linux-kernel@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="KcOlHxOUPHTI2fBm" Content-Disposition: inline In-Reply-To: <20260910-stmmac-fix-vlan-desc-leak-v1-1-6b07dca5e5e8@uniontech.com> X-Proofpoint-GUID: N1uAOD8mrVphpSW42veisobRpvtXb2gR X-Proofpoint-ORIG-GUID: N1uAOD8mrVphpSW42veisobRpvtXb2gR X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTEwMDEwNCBTYWx0ZWRfXwh110cYmaMbm BI/H0Tas0Jp7Dzm/VAknGQU5c72kkgHmPIyhpWR+M/lEzAoDjfnsK383wQg3yM7OTQIDQrtRtgN RBlMQuPlRkOf8RvbrAeu2Z5Q6YX5sg+ziskwcmLeLNzQhmaQIe90y3p5M50Sy+76pWoVi0zp8UA zPasyuYld5GqZNtTKCN/jNJwGxYeejvnxCcFdbW/Ky2yuS3JYMAXfBTQAHQnkt39pt2qcfKHKJw BQ40FeZScC6jWCfiesA2SzhLwNqexhLE7bINkkJG7mS7WEFBuFMk/g6StwQs7BV6ZXUvcVJX9ZT 23+5Cp+FwvoNXWhmulvcDjng1wX4vIUxyOmNm2qeT2Vbf/rdBjf04Iqf2+z2aqwP7NG402Z2ahT J2+V2b60m1yTI0E3WCfEvO8lk3v3XpPpABd6SX5jjFVUYEsv/FAmVBLibn3S6e7oSfW/TLkCoXI Fqoh3ontrDz3+yVRNUw== X-Proofpoint-Spam-Info: AW1haW4tMjYwOTEwMDEwNCBTYWx0ZWRfX8+y030JYBmJ9 EvdSRXSNYrcmCO9ZMe/pJ08sTAjibbFemV+sVsc+JjvlkLqPeKcerXBg5Lqtg9rvSxJah+7HZaZ u4TLWZZct17ffjQLtRZwi0ij/7kxhnM= X-Authority-Analysis: v=2.4 cv=a56lZkSF c=1 sm=1 tr=0 ts=6aa276bf cx=c_pps a=UgVkIMxJMSkC9lv97toC5g==:117 a=WpTaRW6qxYHRGzLzQsVYzg==:17 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=DJpcGTmdVt4CTyJn9g5Z:22 a=iHwBjlyiAAAA:8 a=w8qe9T3wKc6gY-gyingA:9 a=CjuIK1q_8ugA:10 a=dhHhmpoG3uERpqc57R0A:9 a=1HOtulTD9v-eNWfpl4qZ:22 a=uNSKXYNwxGiU6LD0JREI:22 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=2026-09-10_03,2026-09-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 impostorscore=0 priorityscore=1501 spamscore=0 adultscore=0 malwarescore=0 phishscore=0 bulkscore=0 clxscore=1015 suspectscore=0 classifier=typeunknown authscore=0 authtc= authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.22.0-2609040000 definitions=main-2609100104 --KcOlHxOUPHTI2fBm Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable > In stmmac_xmit(), when the DMA mapping of the linear part or of a [...] > if (unlikely(is_jumbo)) { > - entry =3D stmmac_jumbo_frm(priv, tx_q, skb, csum_insertion); > - if (unlikely(entry < 0) && (entry !=3D -EINVAL)) > + ret =3D stmmac_jumbo_frm(priv, tx_q, skb, csum_insertion); if jumbo_frm() returns an error on the subsequent frames, entry is not upda= ted here, so we will end up with a DMA leak. Am I missing something? > + if (unlikely(ret < 0) && (ret !=3D -EINVAL)) > goto dma_map_err; > + entry =3D ret; > } else { > bool last_segment =3D (nfrags =3D=3D 0); > =20 > @@ -4984,6 +4985,26 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb= , struct net_device *dev) > =20 > dma_map_err: > netdev_err(priv->dev, "Tx DMA map failed\n"); > + > + /* entry points one past the last descriptor written for this frame: > + * on failure it is the descriptor whose DMA mapping failed, so walk > + * from first_entry up to, but not including, entry. Reset cur_tx > + * unconditionally as both stmmac_vlan_insert() and stmmac_jumbo_frm() > + * may have advanced it, and release the VLAN context descriptor. > + */ > + while (first_entry !=3D entry) { > + desc =3D stmmac_get_tx_desc(priv, tx_q, first_entry); > + stmmac_release_tx_desc(priv, desc, priv->descriptor_mode); > + stmmac_free_tx_buffer(priv, &priv->dma_conf, queue, first_entry); > + first_entry =3D STMMAC_NEXT_ENTRY(first_entry, > + priv->dma_conf.dma_tx_size); > + } > + > + tx_q->cur_tx =3D first_tx; do we really need to update tx_q->cur_tx here? Regards, Lorenzo > + if (has_vlan) { > + desc =3D stmmac_get_tx_desc(priv, tx_q, first_tx); > + stmmac_release_tx_desc(priv, desc, priv->descriptor_mode); > + } > max_sdu_err: > dev_kfree_skb(skb); > priv->xstats.tx_dropped++; >=20 > --- > base-commit: 893e11787f78e43b534e252249ac3fff4d1333f8 > change-id: 20260909-stmmac-fix-vlan-desc-leak-f057bb061daa >=20 > Best regards, > --=20 > ZhaoJinming >=20 >=20 --KcOlHxOUPHTI2fBm Content-Type: application/pgp-signature; name=signature.asc -----BEGIN PGP SIGNATURE----- iHUEABYKAB0WIQTquNwa3Txd3rGGn7Y6cBh0uS2trAUCaqJ2vAAKCRA6cBh0uS2t rO4sAP9QplCgEOl7LHiJtVRsPPgK9CPA9e9w9UD6ia60BXo9jgD/QCPFa663G/VC TKZ5L1wUNGHzBoI5o+tS5xidHxQsLww= =LJmx -----END PGP SIGNATURE----- --KcOlHxOUPHTI2fBm--