[PATCH 4.19 20/52] vxlan: Fix GRO cells race condition between receive and link delete

From: Greg Kroah-Hartman
Date: Mon Mar 18 2019 - 05:43:15 EST

4.19-stable review patch. If anyone has any objections, please let me know.


From: Stefano Brivio <sbrivio@xxxxxxxxxx>

[ Upstream commit ad6c9986bcb627c7c22b8f9e9a934becc27df87c ]

If we receive a packet while deleting a VXLAN device, there's a chance
vxlan_rcv() is called at the same time as vxlan_dellink(). This is fine,
except that vxlan_dellink() should never ever touch stuff that's still in
use, such as the GRO cells list.

Otherwise, vxlan_rcv() crashes while queueing packets via

Move the gro_cells_destroy() to vxlan_uninit(), which runs after the RCU
grace period is elapsed and nothing needs the gro_cells anymore.

This is now done in the same way as commit 8e816df87997 ("geneve: Use GRO
cells infrastructure.") originally implemented for GENEVE.

Reported-by: Jianlin Shi <jishi@xxxxxxxxxx>
Fixes: 58ce31cca1ff ("vxlan: GRO support at tunnel layer")
Signed-off-by: Stefano Brivio <sbrivio@xxxxxxxxxx>
Reviewed-by: Sabrina Dubroca <sd@xxxxxxxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
drivers/net/vxlan.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -2460,6 +2460,8 @@ static void vxlan_uninit(struct net_devi
struct vxlan_dev *vxlan = netdev_priv(dev);

+ gro_cells_destroy(&vxlan->gro_cells);
vxlan_fdb_delete_default(vxlan, vxlan->cfg.vni);

@@ -3526,7 +3528,6 @@ static void vxlan_dellink(struct net_dev

vxlan_flush(vxlan, true);

- gro_cells_destroy(&vxlan->gro_cells);
unregister_netdevice_queue(dev, head);