From: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
To: kys@microsoft.com, haiyangz@microsoft.com, wei.liu@kernel.org,
decui@microsoft.com, longli@microsoft.com, andrew+netdev@lunn.ch,
davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
pabeni@redhat.com, ernis@linux.microsoft.com,
ssengar@linux.microsoft.com, dipayanroy@linux.microsoft.com,
gargaditya@linux.microsoft.com, shirazsaleem@microsoft.com,
kees@kernel.org, linux-hyperv@vger.kernel.org,
netdev@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH net-next] net: mana: hardening: Validate adapter_mtu from MANA_QUERY_DEV_CONFIG
Date: Thu, 26 Mar 2026 10:30:56 -0700 [thread overview]
Message-ID: <20260326173101.2010514-1-ernis@linux.microsoft.com> (raw)
As a part of MANA hardening for CVM, validate the adapter_mtu value
returned from the MANA_QUERY_DEV_CONFIG HWC command.
The adapter_mtu value is used to compute ndev->max_mtu via:
gc->adapter_mtu - ETH_HLEN. If hardware returns a bogus adapter_mtu
smaller than ETH_HLEN (e.g. 0), the unsigned subtraction wraps to a
huge value, silently allowing oversized MTU settings.
Add a validation check to reject adapter_mtu values below
ETH_MIN_MTU + ETH_HLEN, returning -EPROTO to fail the device
configuration early with a clear error message.
Signed-off-by: Erni Sri Satya Vennela <ernis@linux.microsoft.com>
---
drivers/net/ethernet/microsoft/mana/mana_en.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/net/ethernet/microsoft/mana/mana_en.c b/drivers/net/ethernet/microsoft/mana/mana_en.c
index b39e8b920791..bd07d17a6017 100644
--- a/drivers/net/ethernet/microsoft/mana/mana_en.c
+++ b/drivers/net/ethernet/microsoft/mana/mana_en.c
@@ -1207,10 +1207,16 @@ static int mana_query_device_cfg(struct mana_context *ac, u32 proto_major_ver,
*max_num_vports = resp.max_num_vports;
- if (resp.hdr.response.msg_version >= GDMA_MESSAGE_V2)
+ if (resp.hdr.response.msg_version >= GDMA_MESSAGE_V2) {
+ if (resp.adapter_mtu < ETH_MIN_MTU + ETH_HLEN) {
+ dev_err(dev, "Adapter MTU too small: %u\n",
+ resp.adapter_mtu);
+ return -EPROTO;
+ }
gc->adapter_mtu = resp.adapter_mtu;
- else
+ } else {
gc->adapter_mtu = ETH_FRAME_LEN;
+ }
if (resp.hdr.response.msg_version >= GDMA_MESSAGE_V3)
*bm_hostmode = resp.bm_hostmode;
--
2.34.1
reply other threads:[~2026-03-26 17:31 UTC|newest]
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