[PATCH 0/1] pull request for net: batman-adv 2022-09-16

[PATCH 0/1] pull request for net: batman-adv 2022-09-16

[Simon Wunderlich]

Hi David, hi Jakub,

here is a bugfix for batman-adv which we would like to have integrated into net.

Please pull or let me know of any problem!

Thank you,
      Simon

The following changes since commit 568035b01cfb107af8d2e4bd2fb9aea22cf5b868:

  Linux 6.0-rc1 (2022-08-14 15:50:18 -0700)

are available in the Git repository at:

  git://git.open-mesh.org/linux-merge.git tags/batadv-net-pullrequest-20220916

for you to fetch changes up to b1cb8a71f1eaec4eb77051590f7f561f25b15e32:

  batman-adv: Fix hang up with small MTU hard-interface (2022-08-20 14:17:45 +0200)

----------------------------------------------------------------
Here is a batman-adv bugfix:

 - Fix hang up with small MTU hard-interface, by Shigeru Yoshida

----------------------------------------------------------------
Shigeru Yoshida (1):
      batman-adv: Fix hang up with small MTU hard-interface

 net/batman-adv/hard-interface.c | 4 ++++
 1 file changed, 4 insertions(+)

[PATCH 1/1] batman-adv: Fix hang up with small MTU hard-interface

[Simon Wunderlich]

From: Shigeru Yoshida <syoshida@redhat.com>

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.

Fixes: c6c8fea29769 ("net: Add batman-adv meshing protocol")
Signed-off-by: Shigeru Yoshida <syoshida@redhat.com>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>
---
 net/batman-adv/hard-interface.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/batman-adv/hard-interface.c b/net/batman-adv/hard-interface.c
index b8f8da7ee3de..41c1ad33d009 100644
--- a/net/batman-adv/hard-interface.c
+++ b/net/batman-adv/hard-interface.c
@@ -10,6 +10,7 @@
 #include <linux/atomic.h>
 #include <linux/byteorder/generic.h>
 #include <linux/container_of.h>
+#include <linux/errno.h>
 #include <linux/gfp.h>
 #include <linux/if.h>
 #include <linux/if_arp.h>
@@ -700,6 +701,9 @@ 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;
 
-- 
2.30.2

Re: [PATCH 1/1] batman-adv: Fix hang up with small MTU hard-interface

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by Simon Wunderlich <sw@simonwunderlich.de>:

On Fri, 16 Sep 2022 18:09:31 +0200 you wrote:
> From: Shigeru Yoshida <syoshida@redhat.com>
> 
> 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
> 
> [...]

Here is the summary with links:
  - [1/1] batman-adv: Fix hang up with small MTU hard-interface
    https://git.kernel.org/netdev/net/c/b1cb8a71f1ea

You are awesome, thank you!
-- 
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