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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-acenic@sunsite.dk, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, gszhai@bjtu.edu.cn, 25125332@bjtu.edu.cn, 25125283@bjtu.edu.cn, 23120469@bjtu.edu.cn, stable@vger.kernel.org Subject: Re: [PATCH] net: alteon: Add missing DMA mapping error checks in ace_start_xmit Message-ID: Mail-Followup-To: Joe Damato , Wang Jun <1742789905@qq.com>, Jes Sorensen , Andrew Lunn , "David S . Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-acenic@sunsite.dk, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, gszhai@bjtu.edu.cn, 25125332@bjtu.edu.cn, 25125283@bjtu.edu.cn, 23120469@bjtu.edu.cn, stable@vger.kernel.org References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: On Tue, Mar 31, 2026 at 09:48:41AM +0800, Wang Jun wrote: > The ace_start_xmit function does not check the return value of > dma_map_page (via ace_map_tx_skb) and skb_frag_dma_map when building > transmit descriptors. If mapping fails, an invalid DMA address is > written to the descriptor, which may cause hardware to access > illegal memory, leading to system instability or crashes. > > Add proper dma_mapping_error() checks for all mapping calls. When > mapping fails, free the skb, increment the dropped packet counter, > and return NETDEV_TX_OK. > > Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2") Is this fixing a bug you've seen in the wild? If not, I'd probably drop the fixes tag and send this to net-next instead. > Cc: stable@vger.kernel.org > Signed-off-by: Wang Jun <1742789905@qq.com> > --- > drivers/net/ethernet/alteon/acenic.c | 15 +++++++++++++++ > 1 file changed, 15 insertions(+) > > diff --git a/drivers/net/ethernet/alteon/acenic.c b/drivers/net/ethernet/alteon/acenic.c > index 455ee8930824..acabede53663 100644 > --- a/drivers/net/ethernet/alteon/acenic.c > +++ b/drivers/net/ethernet/alteon/acenic.c > @@ -2417,6 +2417,11 @@ static netdev_tx_t ace_start_xmit(struct sk_buff *skb, > u32 vlan_tag = 0; > > mapping = ace_map_tx_skb(ap, skb, skb, idx); > + if (dma_mapping_error(&ap->pdev->dev, mapping)) { > + dev_kfree_skb(skb); > + dev->stats.tx_dropped++; > + return NETDEV_TX_OK; > + } > flagsize = (skb->len << 16) | (BD_FLG_END); > if (skb->ip_summed == CHECKSUM_PARTIAL) > flagsize |= BD_FLG_TCP_UDP_SUM; > @@ -2438,6 +2443,11 @@ static netdev_tx_t ace_start_xmit(struct sk_buff *skb, > int i; > > mapping = ace_map_tx_skb(ap, skb, NULL, idx); > + if (dma_mapping_error(&ap->pdev->dev, mapping)) { > + dev_kfree_skb(skb); > + dev->stats.tx_dropped++; > + return NETDEV_TX_OK; > + } I am not sure about this. The function ace_map_tx_skb seems to modify a tx_ring_info entry, possibly writing invalid state to it if the dma_map_page fails? Maybe a better fix would be to refactor ace_map_tx_skb and do the dma_mapping_error check there and change the return type of the function and the code flow? Then you wouldn't need to duplicate the error path handling code.