[PATCH net v3 0/1] net: ethernet: lantiq_etop: fix memory disclosure

Changes in v3:
 - back to the use of the temporary 'len' variable

Changes in v2:
 - clarified questions about statistics in the commit description
 - rebased on current master

Aleksander Jan Bajkowski (1):
  net: ethernet: lantiq_etop: fix memory disclosure

 drivers/net/ethernet/lantiq_etop.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

-- 
2.39.5

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 <redacted>
---
 drivers/net/ethernet/lantiq_etop.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/lantiq_etop.c b/drivers/net/ethernet/lantiq_etop.c
index 3c289bfe0a09..7179271f63b6 100644
--- a/drivers/net/ethernet/lantiq_etop.c
+++ b/drivers/net/ethernet/lantiq_etop.c

@@ -481,7 +481,9 @@ ltq_etop_tx(struct sk_buff *skb, struct net_device *dev)
 	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");

-- 
2.39.5

-----Original Message-----
From: Aleksander Jan Bajkowski <redacted>
Sent: Monday, September 23, 2024 2:50 PM
To: davem@davemloft.net; edumazet@google.com; kuba@kernel.org;
pabeni@redhat.com; olek2@wp.pl; horms@kernel.org; Keller, Jacob E
[off-list ref]; john@phrozen.org; ralf@linux-mips.org;
ralph.hempel@lantiq.com; netdev@vger.kernel.org; linux-kernel@vger.kernel.org
Subject: [PATCH net v3 1/1] 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 <redacted>
---

Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>

On 9/23/24 14:49, Aleksander Jan Bajkowski wrote:

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 <redacted>

Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>

Thanks for taking in the suggsetion!
-- 
Florian

On 9/23/24 23:49, Aleksander Jan Bajkowski wrote:

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 <redacted>

For future submissions, please avoid adding the cover letter in case of 
a single patch.

Thanks,

Paolo

Hello:

This patch was applied to netdev/net.git (main)
by Paolo Abeni [off-list ref]:

On Mon, 23 Sep 2024 23:49:48 +0200 you wrote:

Changes in v3:
 - back to the use of the temporary 'len' variable

Changes in v2:
 - clarified questions about statistics in the commit description
 - rebased on current master

[...]

Here is the summary with links:
  - [net,v3,1/1] net: ethernet: lantiq_etop: fix memory disclosure
    https://git.kernel.org/netdev/net/c/45c0de18ff2d

You are awesome, thank you!
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