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[2a03:2880:30ff:4::face:b00c]) by smtp.gmail.com with ESMTPSA id a640c23a62f3a-a7ab04b31ddsm46320966b.60.2024.07.24.01.05.40 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 24 Jul 2024 01:05:40 -0700 (PDT) From: Breno Leitao To: Felix Fietkau , Sean Wang , Mark Lee , Lorenzo Bianconi , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , Matthias Brugger , AngeloGioacchino Del Regno Cc: leit@meta.com, Dan Carpenter , netdev@vger.kernel.org (open list:MEDIATEK ETHERNET DRIVER), linux-kernel@vger.kernel.org (open list:ARM/Mediatek SoC support), linux-arm-kernel@lists.infradead.org (moderated list:ARM/Mediatek SoC support), linux-mediatek@lists.infradead.org (moderated list:ARM/Mediatek SoC support) Subject: [PATCH net] net: mediatek: Fix potential NULL pointer dereference in dummy net_device handling Date: Wed, 24 Jul 2024 01:05:23 -0700 Message-ID: <20240724080524.2734499-1-leitao@debian.org> 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" Move the freeing of the dummy net_device from mtk_free_dev() to mtk_remove(). Previously, if alloc_netdev_dummy() failed in mtk_probe(), eth->dummy_dev would be NULL. The error path would then call mtk_free_dev(), which in turn called free_netdev() assuming dummy_dev was allocated (but it was not), potentially causing a NULL pointer dereference. By moving free_netdev() to mtk_remove(), we ensure it's only called when mtk_probe() has succeeded and dummy_dev is fully allocated. This addresses a potential NULL pointer dereference detected by Smatch[1]. Fixes: b209bd6d0bff ("net: mediatek: mtk_eth_sock: allocate dummy net_devic= e dynamically") Reported-by: Dan Carpenter Closes: https://lore.kernel.org/all/4160f4e0-cbef-4a22-8b5d-42c4d399e1f7@st= anley.mountain/ [1] Suggested-by: Dan Carpenter Reviewed-by: Dan Carpenter Signed-off-by: Breno Leitao Reviewed-by: Simon Horman --- drivers/net/ethernet/mediatek/mtk_eth_soc.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethe= rnet/mediatek/mtk_eth_soc.c index 0cc2dd85652f..16ca427cf4c3 100644 --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c @@ -4223,8 +4223,6 @@ static int mtk_free_dev(struct mtk_eth *eth) metadata_dst_free(eth->dsa_meta[i]); } =20 - free_netdev(eth->dummy_dev); - return 0; } =20 @@ -5090,6 +5088,7 @@ static void mtk_remove(struct platform_device *pdev) netif_napi_del(ð->tx_napi); netif_napi_del(ð->rx_napi); mtk_cleanup(eth); + free_netdev(eth->dummy_dev); mtk_mdio_cleanup(eth); } =20 --=20 2.43.0