Repository : ssh://git@diktynna/batman-adv
On branches: main,stable,main,stable
>---------------------------------------------------------------
commit aeb35331aa9a17f9affd84c1a5b020aeb4a976f4
Author: Sven Eckelmann <sven(a)narfation.org>
Date: Mon Aug 21 21:48:48 2023 +0200
batman-adv: Hold rtnl lock during MTU update via netlink
The automatic recalculation of the maximum allowed MTU is usually triggered
by code sections which are already rtnl lock protected by callers outside
of batman-adv. But when the fragmentation setting is changed via
batman-adv's own batadv genl family, then the rtnl lock is not yet taken.
But dev_set_mtu requires that the caller holds the rtnl lock because it
uses netdevice notifiers. And this code will then fail the check for this
lock:
RTNL: assertion failed at net/core/dev.c (1953)
Cc: stable(a)vger.kernel.org
Reported-by: syzbot+f8812454d9b3ac00d282(a)syzkaller.appspotmail.com
Fixes: 27c4d7c1c7fa ("batman-adv: Trigger events for auto adjusted MTU")
Reviewed-by: Simon Horman <horms(a)kernel.org>
Signed-off-by: Sven Eckelmann <sven(a)narfation.org>
>---------------------------------------------------------------
aeb35331aa9a17f9affd84c1a5b020aeb4a976f4
net/batman-adv/netlink.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c
index 07f21cdb..ae0c42f5 100644
--- a/net/batman-adv/netlink.c
+++ b/net/batman-adv/netlink.c
@@ -495,7 +495,10 @@ static int batadv_netlink_set_mesh(struct sk_buff *skb, struct genl_info *info)
attr = info->attrs[BATADV_ATTR_FRAGMENTATION_ENABLED];
atomic_set(&bat_priv->fragmentation, !!nla_get_u8(attr));
+
+ rtnl_lock();
batadv_update_min_mtu(bat_priv->soft_iface);
+ rtnl_unlock();
}
if (info->attrs[BATADV_ATTR_GW_BANDWIDTH_DOWN]) {