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| author | Di Zhu <zhudi21@huawei.com> | 2021-04-19 21:56:41 +0800 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2021-04-19 16:08:03 -0700 |
| commit | c1102e9d49eb36c0be18cb3e16f6e46ffb717964 (patch) | |
| tree | e481fbf34deb6cf8e86159fd373bc8314e0771f4 | |
| parent | 7ad18ff6449cbd6beb26b53128ddf56d2685aa93 (diff) | |
| download | linux-c1102e9d49eb36c0be18cb3e16f6e46ffb717964.tar.gz linux-c1102e9d49eb36c0be18cb3e16f6e46ffb717964.tar.bz2 linux-c1102e9d49eb36c0be18cb3e16f6e46ffb717964.zip | |
net: fix a data race when get vlan device
We encountered a crash: in the packet receiving process, we got an
illegal VLAN device address, but the VLAN device address saved in vmcore
is correct. After checking the code, we found a possible data
competition:
CPU 0: CPU 1:
(RCU read lock) (RTNL lock)
vlan_do_receive() register_vlan_dev()
vlan_find_dev()
->__vlan_group_get_device() ->vlan_group_prealloc_vid()
In vlan_group_prealloc_vid(), We need to make sure that memset()
in kzalloc() is executed before assigning value to vlan devices array:
=================================
kzalloc()
->memset(object, 0, size)
smp_wmb()
vg->vlan_devices_arrays[pidx][vidx] = array;
==================================
Because __vlan_group_get_device() function depends on this order.
otherwise we may get a wrong address from the hardware cache on
another cpu.
So fix it by adding memory barrier instruction to ensure the order
of memory operations.
Signed-off-by: Di Zhu <zhudi21@huawei.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | net/8021q/vlan.c | 3 | ||||
| -rw-r--r-- | net/8021q/vlan.h | 4 |
2 files changed, 7 insertions, 0 deletions
diff --git a/net/8021q/vlan.c b/net/8021q/vlan.c index 8b644113715e..fb3d3262dc1a 100644 --- a/net/8021q/vlan.c +++ b/net/8021q/vlan.c @@ -71,6 +71,9 @@ static int vlan_group_prealloc_vid(struct vlan_group *vg, if (array == NULL) return -ENOBUFS; + /* paired with smp_rmb() in __vlan_group_get_device() */ + smp_wmb(); + vg->vlan_devices_arrays[pidx][vidx] = array; return 0; } diff --git a/net/8021q/vlan.h b/net/8021q/vlan.h index 953405362795..fa3ad3d4d58c 100644 --- a/net/8021q/vlan.h +++ b/net/8021q/vlan.h @@ -57,6 +57,10 @@ static inline struct net_device *__vlan_group_get_device(struct vlan_group *vg, array = vg->vlan_devices_arrays[pidx] [vlan_id / VLAN_GROUP_ARRAY_PART_LEN]; + + /* paired with smp_wmb() in vlan_group_prealloc_vid() */ + smp_rmb(); + return array ? array[vlan_id % VLAN_GROUP_ARRAY_PART_LEN] : NULL; } |