From 45c0de18ff2dc9af01236380404bbd6a46502c69 Mon Sep 17 00:00:00 2001 From: Aleksander Jan Bajkowski Date: Mon, 23 Sep 2024 23:49:49 +0200 Subject: net: ethernet: lantiq_etop: fix memory disclosure When applying padding, the buffer is not zeroed, which results in memory disclosure. The mentioned data is observed on the wire. This patch uses skb_put_padto() to pad Ethernet frames properly. The mentioned function zeroes the expanded buffer. In case the packet cannot be padded it is silently dropped. Statistics are also not incremented. This driver does not support statistics in the old 32-bit format or the new 64-bit format. These will be added in the future. In its current form, the patch should be easily backported to stable versions. Ethernet MACs on Amazon-SE and Danube cannot do padding of the packets in hardware, so software padding must be applied. Fixes: 504d4721ee8e ("MIPS: Lantiq: Add ethernet driver") Signed-off-by: Aleksander Jan Bajkowski Reviewed-by: Jacob Keller Reviewed-by: Florian Fainelli Link: https://patch.msgid.link/20240923214949.231511-2-olek2@wp.pl Signed-off-by: Paolo Abeni --- drivers/net/ethernet/lantiq_etop.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/drivers/net/ethernet/lantiq_etop.c +++ b/drivers/net/ethernet/lantiq_etop.c @@ -482,7 +482,9 @@ ltq_etop_tx(struct sk_buff *skb, struct unsigned long flags; u32 byte_offset; - len = skb->len < ETH_ZLEN ? ETH_ZLEN : skb->len; + if (skb_put_padto(skb, ETH_ZLEN)) + return NETDEV_TX_OK; + len = skb->len; if ((desc->ctl & (LTQ_DMA_OWN | LTQ_DMA_C)) || ch->skb[ch->dma.desc]) { netdev_err(dev, "tx ring full\n");