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99f62a7460
When calling the RCU brother of br_vlan_get_pvid(), lockdep warns:
=============================
WARNING: suspicious RCU usage
5.9.0-rc3-01631-g13c17acb8e38-dirty #814 Not tainted
-----------------------------
net/bridge/br_private.h:1054 suspicious rcu_dereference_protected() usage!
Call trace:
lockdep_rcu_suspicious+0xd4/0xf8
__br_vlan_get_pvid+0xc0/0x100
br_vlan_get_pvid_rcu+0x78/0x108
The warning is because br_vlan_get_pvid_rcu() calls nbp_vlan_group()
which calls rtnl_dereference() instead of rcu_dereference(). In turn,
rtnl_dereference() calls rcu_dereference_protected() which assumes
operation under an RCU write-side critical section, which obviously is
not the case here. So, when the incorrect primitive is used to access
the RCU-protected VLAN group pointer, READ_ONCE() is not used, which may
cause various unexpected problems.
I'm sad to say that br_vlan_get_pvid() and br_vlan_get_pvid_rcu() cannot
share the same implementation. So fix the bug by splitting the 2
functions, and making br_vlan_get_pvid_rcu() retrieve the VLAN groups
under proper locking annotations.
Fixes:
|
||
|---|---|---|
| .. | ||
| netfilter | ||
| br.c | ||
| br_arp_nd_proxy.c | ||
| br_device.c | ||
| br_fdb.c | ||
| br_forward.c | ||
| br_if.c | ||
| br_input.c | ||
| br_ioctl.c | ||
| br_mdb.c | ||
| br_mrp.c | ||
| br_mrp_netlink.c | ||
| br_mrp_switchdev.c | ||
| br_multicast.c | ||
| br_netfilter_hooks.c | ||
| br_netfilter_ipv6.c | ||
| br_netlink.c | ||
| br_netlink_tunnel.c | ||
| br_nf_core.c | ||
| br_private.h | ||
| br_private_mrp.h | ||
| br_private_stp.h | ||
| br_private_tunnel.h | ||
| br_stp.c | ||
| br_stp_bpdu.c | ||
| br_stp_if.c | ||
| br_stp_timer.c | ||
| br_switchdev.c | ||
| br_sysfs_br.c | ||
| br_sysfs_if.c | ||
| br_vlan.c | ||
| br_vlan_options.c | ||
| br_vlan_tunnel.c | ||
| Kconfig | ||
| Makefile | ||