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net: hsr: require valid EOT supervision TLV

PATCH Applied [email protected] 3 participants 3 messages May 23 – May 27

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Networking Network drivers HSR network protocol
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#0 lore raw

PATCH v7 1/1 net: hsr: require valid EOT supervision TLV

From: Luka Gejak <[email protected]>

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.

Assisted-by Gemini:Gemini-3.1-flash
Signed-off-by Luka Gejak <[email protected]>

---
Changes in v7:
- Send as standalone patch as other patch was moved to net. See NOTE.
NOTE: This patch was previously part of a net-next series and was seperated as requested by Jakub Kicinski. Link to the old series is [1]. [1]:https://lore.kernel.org/netdev/[email protected]/

 net/hsr/hsr_forward.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
net/hsr/hsr_forward.c +1 -1
index f669a226d728..0774981a65c1 100644
@@ -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;
Signature · 1 line
2.54.0
Reviewed-by on v7 1/1
#1 lore raw
Quoted 11 lines · On 5/23/26 3:04 PM, [email protected] wrote:

From: Luka Gejak <[email protected]>

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.

Assisted-by Gemini:Gemini-3.1-flash
Signed-off-by Luka Gejak <[email protected]>
Reviewed-by Fernando Fernandez Mancera <[email protected]>
CI Applied
#2 lore raw
In reply to [email protected]
This patch was applied to netdev/net-next.git (main) by Jakub Kicinski <[email protected]>:

Hello:

This patch was applied to netdev/net-next.git (main) by Jakub Kicinski <[email protected]>:

Quoted 10 lines · On Sat, 23 May 2026 15:04:20 +0200 you wrote:

From: Luka Gejak <[email protected]>

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.

[...]

Here is the summary with links:
- [net-next,v7] net: hsr: require valid EOT supervision TLV

    https://git.kernel.org/netdev/net-next/c/46d111a3ef3b

You are awesome, thank you!

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