From: Shigeru Yoshida <syoshida@redhat.com>
To: mareklindner@neomailbox.ch, sw@simonwunderlich.de, a@unstable.cc,
sven@narfation.org
Cc: b.a.t.m.a.n@lists.open-mesh.org, linux-kernel@vger.kernel.org,
Shigeru Yoshida <syoshida@redhat.com>
Subject: [PATCH] batman-adv: Fix hang up with small MTU hard-interface
Date: Sat, 20 Aug 2022 12:25:16 +0900 [thread overview]
Message-ID: <20220820032516.200446-1-syoshida@redhat.com> (raw)
The system hangs up when batman-adv soft-interface is created on
hard-interface with small MTU. For example, the following commands
create batman-adv soft-interface on dummy interface with zero MTU:
# ip link add name dummy0 type dummy
# ip link set mtu 0 dev dummy0
# ip link set up dev dummy0
# ip link add name bat0 type batadv
# ip link set dev dummy0 master bat0
These commands cause the system hang up with the following messages:
[ 90.578925][ T6689] batman_adv: bat0: Adding interface: dummy0
[ 90.580884][ T6689] batman_adv: bat0: The MTU of interface dummy0 is too small (0) to handle the transport of batman-adv packets. Packets going over this interface will be fragmented on layer2 which could impact the performance. Setting the MTU to 1560 would solve the problem.
[ 90.586264][ T6689] batman_adv: bat0: Interface activated: dummy0
[ 90.590061][ T6689] batman_adv: bat0: Forced to purge local tt entries to fit new maximum fragment MTU (-320)
[ 90.595517][ T6689] batman_adv: bat0: Forced to purge local tt entries to fit new maximum fragment MTU (-320)
[ 90.598499][ T6689] batman_adv: bat0: Forced to purge local tt entries to fit new maximum fragment MTU (-320)
This patch fixes this issue by returning error when enabling
hard-interface with small MTU size.
Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
---
net/batman-adv/hard-interface.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index b8f8da7ee3de..dce5557800e9 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -700,6 +700,9 @@ int batadv_hardif_enable_interface(struct batadv_hard_iface *hard_iface,
int max_header_len = batadv_max_header_len();
int ret;
+ if (hard_iface->net_dev->mtu < ETH_MIN_MTU + max_header_len)
+ return -EINVAL;
+
if (hard_iface->if_status != BATADV_IF_NOT_IN_USE)
goto out;
--
2.37.2
next reply other threads:[~2022-08-20 3:25 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-20 3:25 Shigeru Yoshida [this message]
2022-09-07 16:00 ` [PATCH] batman-adv: Fix hang up with small MTU hard-interface Shigeru Yoshida
2022-09-07 16:04 ` Sven Eckelmann
2022-09-07 16:25 ` [PATCH] batman-adv: Fix hang up with small MTU hard-interface,Re: " Shigeru Yoshida
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