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([187.13.30.172]) by smtp.gmail.com with ESMTPSA id 5a478bee46e88-33e95c7cfd9sm7193489eec.5.2026.09.23.07.12.04 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Sep 2026 07:12:08 -0700 (PDT) From: Aldo Ariel Panzardo To: wei.fang@nxp.com Cc: frank.li@nxp.com, shenwei.wang@nxp.com, imx@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Aldo Ariel Panzardo , Sashiko Subject: [PATCH] net: fec: reject oversized fragments before bounce-buffer memcpy Date: Wed, 23 Sep 2026 11:11:54 -0300 Message-ID: <20260923141154.2415545-1-qwe.aldo@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: imx@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit fec_enet_txq_submit_frag_skb() and fec_enet_txq_submit_skb() copy transmit data into a per-ring bounce buffer when the source address is misaligned or the FEC_QUIRK_SWAP_FRAME quirk is active. The bounce buffers are allocated as kmalloc(FEC_ENET_TX_FRSIZE) where FEC_ENET_TX_FRSIZE is 2048 bytes. However, skb_frag_size() can return up to PAGE_SIZE (4096 on most architectures) for scatter-gather fragments, and skb_headlen() can exceed 2048 for certain GSO packets. When this happens the memcpy overflows the bounce buffer by up to 2048 bytes, corrupting adjacent heap objects. Add a length check before each bounce-buffer copy. If the data exceeds the bounce buffer capacity, fall through to the error path rather than performing the out-of-bounds write. Fixes: 6605b730c061 ("FEC: Add alignment handling for FEC driver") Cc: stable@vger.kernel.org Reported-by: Sashiko Signed-off-by: Aldo Ariel Panzardo --- drivers/net/ethernet/freescale/fec_main.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c index 794ec42..8614984 100644 --- a/drivers/net/ethernet/freescale/fec_main.c +++ b/drivers/net/ethernet/freescale/fec_main.c @@ -558,6 +558,8 @@ fec_enet_txq_submit_frag_skb(struct fec_enet_priv_tx_q *txq, index = fec_enet_get_bd_index(bdp, &txq->bd); if (((unsigned long) bufaddr) & fep->tx_align || fep->quirks & FEC_QUIRK_SWAP_FRAME) { + if (frag_len > FEC_ENET_TX_FRSIZE) + goto dma_mapping_error; memcpy(txq->tx_bounce[index], bufaddr, frag_len); bufaddr = txq->tx_bounce[index]; @@ -634,6 +636,8 @@ static int fec_enet_txq_submit_skb(struct fec_enet_priv_tx_q *txq, index = fec_enet_get_bd_index(bdp, &txq->bd); if (((unsigned long) bufaddr) & fep->tx_align || fep->quirks & FEC_QUIRK_SWAP_FRAME) { + if (buflen > FEC_ENET_TX_FRSIZE) + goto release; memcpy(txq->tx_bounce[index], skb->data, buflen); bufaddr = txq->tx_bounce[index]; -- 2.43.0