2019-07-09 12:16:10

by Dag Moxnes

Subject: [PATCH v4] RDMA/core: Fix race when resolving IP address

Use the neighbour lock when copying the MAC address from the neighbour
data struct in dst_fetch_ha.

When not using the lock, it is possible for the function to race with
neigh_update(), causing it to copy an torn MAC address:

rdma_resolve_addr()
rdma_resolve_ip()
addr_resolve()
addr_resolve_neigh()
fetch_ha()
dst_fetch_ha()
memcpy(dev_addr->dst_dev_addr, n->ha, MAX_ADDR_LEN)

and

net_ioctl()
arp_ioctl()
arp_rec_delete()
arp_invalidate()
neigh_update()
__neigh_update()
memcpy(&neigh->ha, lladdr, dev->addr_len)

It is possible to provoke this error by calling rdma_resolve_addr() in a
tight loop, while deleting the corresponding ARP entry in another tight
loop.

Fixes: 51d45974515c ("infiniband: addr: Consolidate code to fetch neighbour hardware address from dst.")
Signed-off-by: Dag Moxnes <[email protected]>
Signed-off-by: Håkon Bugge <[email protected]>
Reviewed-by: Parav Pandit <[email protected]>
Signed-off-by: Jason Gunthorpe <[email protected]>
---
drivers/infiniband/core/addr.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/infiniband/core/addr.c b/drivers/infiniband/core/addr.c
index 2f7d141598..9b76a8fcdd 100644
--- a/drivers/infiniband/core/addr.c
+++ b/drivers/infiniband/core/addr.c
@@ -337,7 +337,7 @@ static int dst_fetch_ha(const struct dst_entry *dst,
neigh_event_send(n, NULL);
ret = -ENODATA;
} else {
- memcpy(dev_addr->dst_dev_addr, n->ha, MAX_ADDR_LEN);
+ neigh_ha_snapshot(dev_addr->dst_dev_addr, n, dst->dev);
}

neigh_release(n);
--
2.20.1

2019-07-09 19:29:48

by Jason Gunthorpe

Subject: Re: [PATCH v4] RDMA/core: Fix race when resolving IP address

On Tue, Jul 09, 2019 at 01:50:26PM +0200, Dag Moxnes wrote:
> Use the neighbour lock when copying the MAC address from the neighbour
> data struct in dst_fetch_ha.
>
> When not using the lock, it is possible for the function to race with
> neigh_update(), causing it to copy an torn MAC address:
>
> rdma_resolve_addr()
> rdma_resolve_ip()
> addr_resolve()
> addr_resolve_neigh()
> fetch_ha()
> dst_fetch_ha()
> memcpy(dev_addr->dst_dev_addr, n->ha, MAX_ADDR_LEN)
>
> and
>
> net_ioctl()
> arp_ioctl()
> arp_rec_delete()
> arp_invalidate()
> neigh_update()
> __neigh_update()
> memcpy(&neigh->ha, lladdr, dev->addr_len)
>
> It is possible to provoke this error by calling rdma_resolve_addr() in a
> tight loop, while deleting the corresponding ARP entry in another tight
> loop.
>
> Fixes: 51d45974515c ("infiniband: addr: Consolidate code to fetch neighbour hardware address from dst.")
> Signed-off-by: Dag Moxnes <[email protected]>
> Signed-off-by: Håkon Bugge <[email protected]>
> Reviewed-by: Parav Pandit <[email protected]>
> Signed-off-by: Jason Gunthorpe <[email protected]>
> ---
> drivers/infiniband/core/addr.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)

Applied to for-next, thanks

Jason