[PATCH net-next v6 0/2] net: hsr: strict supervision TLV validation

[PATCH net-next v6 0/2] net: hsr: strict supervision TLV validation

[luka.gejak]

From: Luka Gejak <luka.gejak@linux.dev>

Changes in v6:
 - Dropped capitalization comment changes per request of Jakub Kicinski

Changes in v5:
 - Reverted TLV loop in Patch 1 to strict sequential parsing per IEC
   62439-3.
 - Retained pskb_may_pull() logic to ensure memory safety for TLV
   headers.
 - Dropped Reviewed-by from Patch 1 due to the logic evolving since
   original review.
 - Added Assisted-by tag for AI-aided translation and formatting to
   both patches.

Changes in v4:
 - Split from a 4-patch series into 'net' and 'net-next' as requested.
 - Implemented a TLV walker in Patch 1 to correctly handle extension
   TLVs and avoid regressions on paged frames/non-linearized skbs.
 - Corrected pskb_may_pull() logic to include the TLV header size.

History of pre-separation series (v1-v3):
Changes in v3:
 - addressed Felix review feedback in the VLAN add unwind fix
 - removed the superfluous empty line

Changes in v2:
 - picked up Reviewed-by tags on patches 1, 3 and 4
 - changes in patch 2 per advice of Felix Maurer

Luka Gejak (2):
  net: hsr: require valid EOT supervision TLV
  net: hsr: reject unresolved interlink ifindex

 net/hsr/hsr_forward.c | 6 +++---
 net/hsr/hsr_netlink.c | 7 ++++++-
 2 files changed, 9 insertions(+), 4 deletions(-)

-- 
2.53.0

[PATCH net-next v6 1/2] net: hsr: require valid EOT supervision TLV

[luka.gejak]

From: Luka Gejak <luka.gejak@linux.dev>

Supervision frames are only valid if terminated with a zero-length EOT
TLV. The current check fails to reject non-EOT entries as the terminal
TLV, potentially allowing malformed supervision traffic.

Fix this by strictly requiring the terminal TLV to be HSR_TLV_EOT
with a length of zero, and properly linearizing the TLV header before
access.

Assisted-by: Gemini:Gemini-3.1-flash
Signed-off-by: Luka Gejak <luka.gejak@linux.dev>
---
 net/hsr/hsr_forward.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/hsr/hsr_forward.c b/net/hsr/hsr_forward.c
index 0aca859c88cb..0774981a65c1 100644
--- a/net/hsr/hsr_forward.c
+++ b/net/hsr/hsr_forward.c
@@ -84,7 +84,7 @@ static bool is_supervision_frame(struct hsr_priv *hsr, struct sk_buff *skb)
 
 	/* Get next tlv */
 	total_length += hsr_sup_tag->tlv.HSR_TLV_length;
-	if (!pskb_may_pull(skb, total_length))
+	if (!pskb_may_pull(skb, total_length + sizeof(struct hsr_sup_tlv)))
 		return false;
 	skb_pull(skb, total_length);
 	hsr_sup_tlv = (struct hsr_sup_tlv *)skb->data;
@@ -100,7 +100,7 @@ static bool is_supervision_frame(struct hsr_priv *hsr, struct sk_buff *skb)
 
 		/* make sure another tlv follows */
 		total_length += sizeof(struct hsr_sup_tlv) + hsr_sup_tlv->HSR_TLV_length;
-		if (!pskb_may_pull(skb, total_length))
+		if (!pskb_may_pull(skb, total_length + sizeof(struct hsr_sup_tlv)))
 			return false;
 
 		/* get next tlv */
@@ -110,7 +110,7 @@ static bool is_supervision_frame(struct hsr_priv *hsr, struct sk_buff *skb)
 	}
 
 	/* end of tlvs must follow at the end */
-	if (hsr_sup_tlv->HSR_TLV_type == HSR_TLV_EOT &&
+	if (hsr_sup_tlv->HSR_TLV_type != HSR_TLV_EOT ||
 	    hsr_sup_tlv->HSR_TLV_length != 0)
 		return false;
 
-- 
2.53.0

Re: [PATCH net-next v6 1/2] net: hsr: require valid EOT supervision TLV

[Felix Maurer]

On Mon, Apr 13, 2026 at 12:34:48PM +0200, luka.gejak@linux.dev wrote:
> From: Luka Gejak <luka.gejak@linux.dev>
>
> Supervision frames are only valid if terminated with a zero-length EOT
> TLV. The current check fails to reject non-EOT entries as the terminal
> TLV, potentially allowing malformed supervision traffic.
>
> Fix this by strictly requiring the terminal TLV to be HSR_TLV_EOT
> with a length of zero, and properly linearizing the TLV header before
> access.
>
> Assisted-by: Gemini:Gemini-3.1-flash
> Signed-off-by: Luka Gejak <luka.gejak@linux.dev>

Please respect the netdev development process [1], net-next is currently
closed. I'll leave it to the maintainers if a resubmission is required.

Other than that:
Reviewed-by: Felix Maurer <fmaurer@redhat.com>

Thanks,
   Felix


[1]: https://docs.kernel.org/process/maintainer-netdev.html#git-trees-and-patch-flow

> ---
>  net/hsr/hsr_forward.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/net/hsr/hsr_forward.c b/net/hsr/hsr_forward.c
> index 0aca859c88cb..0774981a65c1 100644
> --- a/net/hsr/hsr_forward.c
> +++ b/net/hsr/hsr_forward.c
> @@ -84,7 +84,7 @@ static bool is_supervision_frame(struct hsr_priv *hsr, struct sk_buff *skb)
>
>  	/* Get next tlv */
>  	total_length += hsr_sup_tag->tlv.HSR_TLV_length;
> -	if (!pskb_may_pull(skb, total_length))
> +	if (!pskb_may_pull(skb, total_length + sizeof(struct hsr_sup_tlv)))
>  		return false;
>  	skb_pull(skb, total_length);
>  	hsr_sup_tlv = (struct hsr_sup_tlv *)skb->data;
> @@ -100,7 +100,7 @@ static bool is_supervision_frame(struct hsr_priv *hsr, struct sk_buff *skb)
>
>  		/* make sure another tlv follows */
>  		total_length += sizeof(struct hsr_sup_tlv) + hsr_sup_tlv->HSR_TLV_length;
> -		if (!pskb_may_pull(skb, total_length))
> +		if (!pskb_may_pull(skb, total_length + sizeof(struct hsr_sup_tlv)))
>  			return false;
>
>  		/* get next tlv */
> @@ -110,7 +110,7 @@ static bool is_supervision_frame(struct hsr_priv *hsr, struct sk_buff *skb)
>  	}
>
>  	/* end of tlvs must follow at the end */
> -	if (hsr_sup_tlv->HSR_TLV_type == HSR_TLV_EOT &&
> +	if (hsr_sup_tlv->HSR_TLV_type != HSR_TLV_EOT ||
>  	    hsr_sup_tlv->HSR_TLV_length != 0)
>  		return false;
>
> --
> 2.53.0
>

[PATCH net-next v6 2/2] net: hsr: reject unresolved interlink ifindex

[luka.gejak]

From: Luka Gejak <luka.gejak@linux.dev>

In hsr_newlink(), a provided but invalid IFLA_HSR_INTERLINK attribute
was silently ignored if __dev_get_by_index() returned NULL. This leads
to incorrect RedBox topology creation without notifying the user.

Fix this by returning -EINVAL and an extack message when the
interlink attribute is present but cannot be resolved.

Assisted-by: Gemini:Gemini-3.1-flash
Reviewed-by: Felix Maurer <fmaurer@redhat.com>
Signed-off-by: Luka Gejak <luka.gejak@linux.dev>
---
 net/hsr/hsr_netlink.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/net/hsr/hsr_netlink.c b/net/hsr/hsr_netlink.c
index db0b0af7a692..f0ca23da3ab9 100644
--- a/net/hsr/hsr_netlink.c
+++ b/net/hsr/hsr_netlink.c
@@ -76,9 +76,14 @@ static int hsr_newlink(struct net_device *dev,
 		return -EINVAL;
 	}
 
-	if (data[IFLA_HSR_INTERLINK])
+	if (data[IFLA_HSR_INTERLINK]) {
 		interlink = __dev_get_by_index(link_net,
 					       nla_get_u32(data[IFLA_HSR_INTERLINK]));
+		if (!interlink) {
+			NL_SET_ERR_MSG_MOD(extack, "Interlink does not exist");
+			return -EINVAL;
+		}
+	}
 
 	if (interlink && interlink == link[0]) {
 		NL_SET_ERR_MSG_MOD(extack, "Interlink and Slave1 are the same");
-- 
2.53.0