[PATCH net v2] net: dsa: tag_ocelot_8021q: fix broken reception

[PATCH net v2] net: dsa: tag_ocelot_8021q: fix broken reception

[Robert Hodaszi]

The blamed commit changed the dsa_8021q_rcv() calling convention to
accept pre-populated source_port and switch_id arguments. If those are
not available, as in the case of tag_ocelot_8021q, the arguments must be
pre-initialized with -1.

Due to the bug of passing uninitialized arguments in tag_ocelot_8021q,
dsa_8021q_rcv() does not detect that it needs to populate the
source_port and switch_id, and this makes dsa_conduit_find_user() fail,
which leads to packet loss on reception.

Fixes: dcfe7673787b ("net: dsa: tag_sja1105: absorb logic for not overwriting precise info into dsa_8021q_rcv()")
Signed-off-by: Robert Hodaszi <robert.hodaszi@digi.com>
---
Cc: stable@vger.kernel.org
---
 net/dsa/tag_ocelot_8021q.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/dsa/tag_ocelot_8021q.c b/net/dsa/tag_ocelot_8021q.c
index 8e8b1bef6af6..11ea8cfd6266 100644
--- a/net/dsa/tag_ocelot_8021q.c
+++ b/net/dsa/tag_ocelot_8021q.c
@@ -79,7 +79,7 @@ static struct sk_buff *ocelot_xmit(struct sk_buff *skb,
 static struct sk_buff *ocelot_rcv(struct sk_buff *skb,
 				  struct net_device *netdev)
 {
-	int src_port, switch_id;
+	int src_port = -1, switch_id = -1;
 
 	dsa_8021q_rcv(skb, &src_port, &switch_id, NULL, NULL);
 
-- 
2.43.0

Re: [PATCH net v2] net: dsa: tag_ocelot_8021q: fix broken reception

[Vladimir Oltean]

On Wed, Dec 11, 2024 at 03:47:41PM +0100, Robert Hodaszi wrote:
> The blamed commit changed the dsa_8021q_rcv() calling convention to
> accept pre-populated source_port and switch_id arguments. If those are
> not available, as in the case of tag_ocelot_8021q, the arguments must be
> pre-initialized with -1.
> 
> Due to the bug of passing uninitialized arguments in tag_ocelot_8021q,
> dsa_8021q_rcv() does not detect that it needs to populate the
> source_port and switch_id, and this makes dsa_conduit_find_user() fail,
> which leads to packet loss on reception.
> 
> Fixes: dcfe7673787b ("net: dsa: tag_sja1105: absorb logic for not overwriting precise info into dsa_8021q_rcv()")
> Signed-off-by: Robert Hodaszi <robert.hodaszi@digi.com>
> ---

Reviewed-by: Vladimir Oltean <vladimir.oltean@nxp.com>

Re: [PATCH net v2] net: dsa: tag_ocelot_8021q: fix broken reception

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (main)
by Jakub Kicinski <kuba@kernel.org>:

On Wed, 11 Dec 2024 15:47:41 +0100 you wrote:
> The blamed commit changed the dsa_8021q_rcv() calling convention to
> accept pre-populated source_port and switch_id arguments. If those are
> not available, as in the case of tag_ocelot_8021q, the arguments must be
> pre-initialized with -1.
> 
> Due to the bug of passing uninitialized arguments in tag_ocelot_8021q,
> dsa_8021q_rcv() does not detect that it needs to populate the
> source_port and switch_id, and this makes dsa_conduit_find_user() fail,
> which leads to packet loss on reception.
> 
> [...]

Here is the summary with links:
  - [net,v2] net: dsa: tag_ocelot_8021q: fix broken reception
    https://git.kernel.org/netdev/net/c/36ff681d2283

You are awesome, thank you!
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