Hi Jason,
Thanks for the review.
On 6/21/19 4:56 PM, Jason Gunthorpe wrote:
On Fri, Jun 21, 2019 at 04:09:16PM +0200, Dag Moxnes wrote:
Use neighbour lock when copying MAC address from 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 invalid MAC address.
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.
Signed-off-by: Dag Moxnes <dag.moxnes@xxxxxxxxxx>
Change-Id: I3c5f982b304457f0a83ea7def2fac70315ed38b4
drivers/infiniband/core/addr.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/infiniband/core/addr.c b/drivers/infiniband/core/addr.c
index 2f7d141598..e4945fd1bb 100644
+++ b/drivers/infiniband/core/addr.c
@@ -333,12 +333,16 @@ static int dst_fetch_ha(const struct dst_entry *dst,
if (!n)
return -ENODATA;
+ read_lock_bh(&n->lock)
Miising semicolon at end of statement. Sorry about that.
if (!(n->nud_state & NUD_VALID)) {
- neigh_event_send(n, NULL);
ret = -ENODATA;
} else {
memcpy(dev_addr->dst_dev_addr, n->ha, MAX_ADDR_LEN);
}
+ read_unlock_bh(&n->lock);
+
+ if (ret)
+ neigh_event_send(n, NULL);
neigh_release(n);
Can we write this with less spaghetti please, maybe:
static int dst_fetch_ha(const struct dst_entry *dst,
struct rdma_dev_addr *dev_addr,
const void *daddr)
{
struct neighbour *n;
int ret = 0;
n = dst_neigh_lookup(dst, daddr);
if (!n)
return -ENODATA;
read_lock_bh(&n->lock);
if (!(n->nud_state & NUD_VALID)) {
read_unlock_bh(&n->lock);
goto out_send;
}
memcpy(dev_addr->dst_dev_addr, n->ha, MAX_ADDR_LEN);
read_unlock_bh(&n->lock);
goto out_release;
out_send:
neigh_event_send(n, NULL);
ret = -ENODATA;
out_release:
neigh_release(n);
return ret;
}
Personally I find it more readable when the unlock is done in one place,
but sure, I can rewrite it the way you suggest if the reviewers agree that
that way is preferable.
Regards,
-Dag
Also, Parav should look at it.
Thanks,
Jason
