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authorSven Eckelmann <sven@narfation.org>2023-08-21 21:48:48 +0200
committerJakub Kicinski <kuba@kernel.org>2023-08-22 17:25:10 -0700
commit987aae75fc1041072941ffb622b45ce2359a99b9 (patch)
treed6e3727e56c67b83ded6d42f358be5e61db89d1b
parentb888c510f7b3d64ca75fc0f43b4a4bd1a611312f (diff)
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: c6a953cce8d0 ("batman-adv: Trigger events for auto adjusted MTU") Signed-off-by: Sven Eckelmann <sven@narfation.org> Reviewed-by: Simon Horman <horms@kernel.org> Link: https://lore.kernel.org/r/20230821-batadv-missing-mtu-rtnl-lock-v1-1-1c5a7bfe861e@narfation.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>
-rw-r--r--net/batman-adv/netlink.c3
1 files changed, 3 insertions, 0 deletions
diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c
index ad5714f737be..6efbc9275aec 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]) {