From 364379c056ca41a77ae62e5ce4fb0d7d8e8e8459 Mon Sep 17 00:00:00 2001 From: Sven Eckelmann Date: Tue, 22 Aug 2023 18:26:35 +0200 Subject: [PATCH] batman-adv: Fix lock assert after fragmentation change 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) Fixes: e7ee4c55ded3 ("batman-adv: update to version 2023.2") Signed-off-by: Sven Eckelmann --- batman-adv/Makefile | 2 +- ...rtnl-lock-during-MTU-update-via-netl.patch | 34 +++++++++++++++++++ 2 files changed, 35 insertions(+), 1 deletion(-) create mode 100644 batman-adv/patches/0003-batman-adv-Hold-rtnl-lock-during-MTU-update-via-netl.patch diff --git a/batman-adv/Makefile b/batman-adv/Makefile index f00bbb5..84adf6e 100644 --- a/batman-adv/Makefile +++ b/batman-adv/Makefile @@ -4,7 +4,7 @@ include $(TOPDIR)/rules.mk PKG_NAME:=batman-adv PKG_VERSION:=2023.2 -PKG_RELEASE:=1 +PKG_RELEASE:=2 PKG_SOURCE:=$(PKG_NAME)-$(PKG_VERSION).tar.gz PKG_SOURCE_URL:=https://downloads.open-mesh.org/batman/releases/batman-adv-$(PKG_VERSION) diff --git a/batman-adv/patches/0003-batman-adv-Hold-rtnl-lock-during-MTU-update-via-netl.patch b/batman-adv/patches/0003-batman-adv-Hold-rtnl-lock-during-MTU-update-via-netl.patch new file mode 100644 index 0000000..4d7a392 --- /dev/null +++ b/batman-adv/patches/0003-batman-adv-Hold-rtnl-lock-during-MTU-update-via-netl.patch @@ -0,0 +1,34 @@ +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 + +--- a/net/batman-adv/netlink.c ++++ b/net/batman-adv/netlink.c +@@ -495,7 +495,10 @@ 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]) {