This is a note to let you know that I've just added the patch titled
batman-adv: Hold rtnl lock during MTU update via netlink
to the 6.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
batman-adv-hold-rtnl-lock-during-mtu-update-via-netlink.patch
and it can be found in the queue-6.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 987aae75fc1041072941ffb622b45ce2359a99b9 Mon Sep 17 00:00:00 2001
From: Sven Eckelmann <sven@xxxxxxxxxxxxx>
Date: Mon, 21 Aug 2023 21:48:48 +0200
Subject: batman-adv: Hold rtnl lock during MTU update via netlink
From: Sven Eckelmann <sven@xxxxxxxxxxxxx>
commit 987aae75fc1041072941ffb622b45ce2359a99b9 upstream.
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@xxxxxxxxxxxxxxx
Reported-by: syzbot+f8812454d9b3ac00d282@xxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: c6a953cce8d0 ("batman-adv: Trigger events for auto adjusted MTU")
Signed-off-by: Sven Eckelmann <sven@xxxxxxxxxxxxx>
Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20230821-batadv-missing-mtu-rtnl-lock-v1-1-1c5a7bfe861e@xxxxxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/batman-adv/netlink.c | 3 +++
1 file changed, 3 insertions(+)
--- 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]) {
Patches currently in stable-queue which might be from sven@xxxxxxxxxxxxx are
queue-6.4/batman-adv-fix-tt-global-entry-leak-when-client-roamed-back.patch
queue-6.4/batman-adv-don-t-increase-mtu-when-set-by-user.patch
queue-6.4/batman-adv-do-not-get-eth-header-before-batadv_check_management_packet.patch
queue-6.4/batman-adv-trigger-events-for-auto-adjusted-mtu.patch
queue-6.4/batman-adv-hold-rtnl-lock-during-mtu-update-via-netlink.patch
queue-6.4/batman-adv-fix-batadv_v_ogm_aggr_send-memory-leak.patch
