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[24.12.10.127]) by smtp.gmail.com with ESMTPSA id 6a1803df08f44-89c96cb614dsm2999406d6.22.2026.03.20.20.54.49 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 20 Mar 2026 20:54:51 -0700 (PDT) From: Tyllis Xu X-Google-Original-From: Tyllis Xu To: netdev@vger.kernel.org Cc: haren@linux.ibm.com, ricklind@linux.ibm.com, nnac123@linux.ibm.com, sukadev@linux.ibm.com, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, andrew+netdev@lunn.ch, stable@vger.kernel.org, linux-kernel@vger.kernel.org, danisjiang@gmail.com, ychen@northwestern.edu, Tyllis Xu Subject: [PATCH] ibmvnic: fix OOB array access in ibmvnic_xmit on queue count reduction Date: Fri, 20 Mar 2026 22:54:39 -0500 Message-ID: <20260321035439.900644-1-LivelyCarpet87@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When the number of TX queues is reduced (e.g., via ethtool -L), the Qdisc layer retains previously enqueued skbs with queue mappings from before the reduction. After the reset completes and tx_queues_active is set to true, netif_tx_start_all_queues() drains these stale skbs through ibmvnic_xmit(). The queue index from skb_get_queue_mapping() may exceed the newly allocated array bounds, causing out-of-bounds reads on tx_scrq[] and tx_pool[]/tso_pool[], and out-of-bounds writes on tx_stats_buffers[] in the function's exit path. The existing tx_queues_active guard does not help here: it is set to true by __ibmvnic_open() before netif_tx_start_all_queues() restarts queue draining, so stale skbs pass the check with an invalid queue index. Add a bounds check against num_active_tx_scrqs immediately after the tx_queues_active guard. Use a dedicated out_unlock label to skip the per-queue stats updates (which also index tx_stats_buffers[queue_num]) when the queue index is invalid. Fixes: 4219196d1f66 ("ibmvnic: fix race between xmit and reset") Reported-by: Yuhao Jiang Cc: stable@vger.kernel.org Signed-off-by: Tyllis Xu --- drivers/net/ethernet/ibm/ibmvnic.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/drivers/net/ethernet/ibm/ibmvnic.c b/drivers/net/ethernet/ibm/= ibmvnic.c index 5a510eed335e..c939391474cb 100644 --- a/drivers/net/ethernet/ibm/ibmvnic.c +++ b/drivers/net/ethernet/ibm/ibmvnic.c @@ -2453,6 +2453,11 @@ static netdev_tx_t ibmvnic_xmit(struct sk_buff *skb,= struct net_device *netdev) goto out; } =20 + if (unlikely(queue_num >=3D adapter->num_active_tx_scrqs)) { + dev_kfree_skb_any(skb); + goto out_unlock; + } + tx_scrq =3D adapter->tx_scrq[queue_num]; txq =3D netdev_get_tx_queue(netdev, queue_num); ind_bufp =3D &tx_scrq->ind_buf; @@ -2672,6 +2677,9 @@ static netdev_tx_t ibmvnic_xmit(struct sk_buff *skb, = struct net_device *netdev) adapter->tx_stats_buffers[queue_num].bytes +=3D tx_bytes; adapter->tx_stats_buffers[queue_num].dropped_packets +=3D tx_dropped; =20 + return ret; +out_unlock: + rcu_read_unlock(); return ret; } =20 --=20 2.43.0