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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: 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="KcOlHxOUPHTI2fBm" Content-Disposition: inline In-Reply-To: <20260910-stmmac-fix-vlan-desc-leak-v1-1-6b07dca5e5e8@uniontech.com> X-Proofpoint-GUID: M_jsUiN9wSu-ookVrK0ztdEZemd4Nccr X-Authority-Analysis: v=2.4 cv=ef+o7LEH c=1 sm=1 tr=0 ts=6aa276bf cx=c_pps a=HLyN3IcIa5EE8TELMZ618Q==:117 a=WpTaRW6qxYHRGzLzQsVYzg==:17 a=VdqzKS8jKosA:10 a=s4-Qcg_JpJYA:10 a=VkNPw1HP01LnGYTKEx00:22 a=u7WPNUs3qKkmUXheDGA7:22 a=rJkE3RaqiGZ5pbrm-msn:22 a=iHwBjlyiAAAA:8 a=w8qe9T3wKc6gY-gyingA:9 a=CjuIK1q_8ugA:10 a=dhHhmpoG3uERpqc57R0A:9 a=bTQJ7kPSJx9SKPbeHEYW:22 a=uNSKXYNwxGiU6LD0JREI:22 X-Proofpoint-ORIG-GUID: M_jsUiN9wSu-ookVrK0ztdEZemd4Nccr X-Proofpoint-Spam-Info: AW1haW4tMjYwOTEwMDEwNCBTYWx0ZWRfX8jg6X70gsdBP XAP0sRu+IIQal6ZcrUPyHcAcYrr0iKykrmB0TvHy+1zKDvHgtT70udL4t7ggnpZixhRafJgFNYV O/fU0iVfzT7HXWKkM4XCQsYCjLLuPo8= X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwOTEwMDEwNCBTYWx0ZWRfX5UOCwjfOk1xN kVU3QZ7Vn5CcoZHSPzT6O5YNcz+eaPl6ygOCbQoGrsUVTGsui4/HYTODyAMyL482hp9rIgzj1JA ltQlVzC1vz4PLBLbmkgDSmsUwNABkBzeMFUBA6vAc/4Ksbw3nfyvT3HxzdUiha6v+ah9bn5Kk67 nJImRtnuG8H9P5SOKcdhEArsJ1BPQn7BT5JdY4Bpy82FwdfjOomaG67tfvQcGX9qCDLHaYMzWid hiEbArt6f3bx3Sr0p8Frzu8t0BbY3Ox2Gx4t8SM8zqsHljro5QYazoRItawBcSUDomQSx3XqtYT mWaqt0ESGsoUsxDhl6ytbIQ67TMTdDwmt94Zh7b9spxNoCMHo3gnSLC/4NteoNdOj9laXUoh2dz B/VT1OI5TB7SNiZpzbJmE8wtrXI3J8EvM5dX1c4NFKndRmsXHn+LcZ94jkT1s6M9RcKsKbj1eqM GKqa7i9hrJOzPczHgpQ== 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 malwarescore=0 suspectscore=0 adultscore=0 priorityscore=1501 lowpriorityscore=0 clxscore=1015 phishscore=0 impostorscore=0 bulkscore=0 spamscore=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--