diff --git a/batman-adv/patches/0010-batman-adv-Hold-rtnl-lock-during-MTU-update-via-netl.patch b/batman-adv/patches/0010-batman-adv-Hold-rtnl-lock-during-MTU-update-via-netl.patch new file mode 100644 index 000000000..954d9187b --- /dev/null +++ b/batman-adv/patches/0010-batman-adv-Hold-rtnl-lock-during-MTU-update-via-netl.patch @@ -0,0 +1,36 @@ +From: Sven Eckelmann +Date: Mon, 21 Aug 2023 21:48:48 +0200 +Subject: 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@vger.kernel.org +Reported-by: syzbot+f8812454d9b3ac00d282@syzkaller.appspotmail.com +Fixes: 27c4d7c1c7fa ("batman-adv: Trigger events for auto adjusted MTU") +Reviewed-by: Simon Horman +Signed-off-by: Sven Eckelmann +Origin: upstream, https://git.open-mesh.org/batman-adv.git/commit/aeb35331aa9a17f9affd84c1a5b020aeb4a976f4 +(cherry picked from commit ae89872e52a07063b652f3db12f5e7d599f266fe) + +--- a/net/batman-adv/netlink.c ++++ b/net/batman-adv/netlink.c +@@ -494,7 +494,10 @@ static int batadv_netlink_set_mesh(struc + 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]) {