Reset MAC header in case of using dev_direct_xmit(), e.g. by specifying
PACKET_QDISC_BYPASS. This is needed, because other code such as the HSR layer
expects the MAC header to be correctly set.
This has been observed using the following setup:
|$ ip link add name hsr0 type hsr slave1 lan0 slave2 lan1 supervision 45
version 1
|$ ifconfig hsr0 up
|$ ./test hsr0
The test binary is using mmap'ed sockets and is specifying the
PACKET_QDISC_BYPASS socket option.
This patch resolves the following warning on a non-patched kernel:
|[ 112.725394] ------------[ cut here ]------------
|[ 112.731418] WARNING: CPU: 1 PID: 257 at net/hsr/hsr_forward.c:560
hsr_forward_skb+0x484/0x568
|[ 112.739962] net/hsr/hsr_forward.c:560: Malformed frame (port_src hsr0)
The MAC header is also reset unconditionally in case of PACKET_QDISC_BYPASS is
not used at the top of __dev_queue_xmit().
Fixes: d346a3fae3ff ("packet: introduce PACKET_QDISC_BYPASS socket option")
Signed-off-by: Kurt Kanzenbach <k...@linutronix.de>
---
Changes since v1:
* Move skb_reset_mac_header() to __dev_direct_xmit()
* Add Fixes tag
* Target net tree
Previous versions:
* https://lkml.kernel.org/netdev/20210326154835.21296-1-k...@linutronix.de/
net/core/dev.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/net/core/dev.c b/net/core/dev.c
index b4c67a5be606..b5088223dc57 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -4297,6 +4297,8 @@ int __dev_direct_xmit(struct sk_buff *skb, u16 queue_id)
!netif_carrier_ok(dev)))
goto drop;
+ skb_reset_mac_header(skb);
+
skb = validate_xmit_skb_list(skb, dev, &again);
if (skb != orig_skb)
goto drop;
--
2.20.1
