| Message ID | 29c4b0e67dc1bf3571df3982de87df90cae9b631.1696837310.git.jk@codeconstruct.com.au (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 5093bbfc10ab6636b32728e35813cbd79feb063c |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | [net] mctp: perform route lookups under a RCU read-side lock | expand |
On Mon, Oct 9, 2023 at 9:57 AM Jeremy Kerr <jk@codeconstruct.com.au> wrote: > > Our current route lookups (mctp_route_lookup and mctp_route_lookup_null) > traverse the net's route list without the RCU read lock held. This means > the route lookup is subject to preemption, resulting in an potential > grace period expiry, and so an eventual kfree() while we still have the > route pointer. > > Add the proper read-side critical section locks around the route > lookups, preventing premption and a possible parallel kfree. > > The remaining net->mctp.routes accesses are already under a > rcu_read_lock, or protected by the RTNL for updates. > > Based on an analysis from Sili Luo <rootlab@huawei.com>, where > introducing a delay in the route lookup could cause a UAF on > simultaneous sendmsg() and route deletion. > > Reported-by: Sili Luo <rootlab@huawei.com> > Fixes: 889b7da23abf ("mctp: Add initial routing framework") > Cc: stable@vger.kernel.org > Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au> > --- > Reviewed-by: Eric Dumazet <edumazet@google.com>
Hello: This patch was applied to netdev/net.git (main) by Jakub Kicinski <kuba@kernel.org>: On Mon, 9 Oct 2023 15:56:45 +0800 you wrote: > Our current route lookups (mctp_route_lookup and mctp_route_lookup_null) > traverse the net's route list without the RCU read lock held. This means > the route lookup is subject to preemption, resulting in an potential > grace period expiry, and so an eventual kfree() while we still have the > route pointer. > > Add the proper read-side critical section locks around the route > lookups, preventing premption and a possible parallel kfree. > > [...] Here is the summary with links: - [net] mctp: perform route lookups under a RCU read-side lock https://git.kernel.org/netdev/net/c/5093bbfc10ab You are awesome, thank you!
diff --git a/net/mctp/route.c b/net/mctp/route.c index f51a05ec7162..68be8f2b622d 100644 --- a/net/mctp/route.c +++ b/net/mctp/route.c @@ -737,6 +737,8 @@ struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet, { struct mctp_route *tmp, *rt = NULL; + rcu_read_lock(); + list_for_each_entry_rcu(tmp, &net->mctp.routes, list) { /* TODO: add metrics */ if (mctp_rt_match_eid(tmp, dnet, daddr)) { @@ -747,21 +749,29 @@ struct mctp_route *mctp_route_lookup(struct net *net, unsigned int dnet, } } + rcu_read_unlock(); + return rt; } static struct mctp_route *mctp_route_lookup_null(struct net *net, struct net_device *dev) { - struct mctp_route *rt; + struct mctp_route *tmp, *rt = NULL; - list_for_each_entry_rcu(rt, &net->mctp.routes, list) { - if (rt->dev->dev == dev && rt->type == RTN_LOCAL && - refcount_inc_not_zero(&rt->refs)) - return rt; + rcu_read_lock(); + + list_for_each_entry_rcu(tmp, &net->mctp.routes, list) { + if (tmp->dev->dev == dev && tmp->type == RTN_LOCAL && + refcount_inc_not_zero(&tmp->refs)) { + rt = tmp; + break; + } } - return NULL; + rcu_read_unlock(); + + return rt; } static int mctp_do_fragment_route(struct mctp_route *rt, struct sk_buff *skb,
Our current route lookups (mctp_route_lookup and mctp_route_lookup_null) traverse the net's route list without the RCU read lock held. This means the route lookup is subject to preemption, resulting in an potential grace period expiry, and so an eventual kfree() while we still have the route pointer. Add the proper read-side critical section locks around the route lookups, preventing premption and a possible parallel kfree. The remaining net->mctp.routes accesses are already under a rcu_read_lock, or protected by the RTNL for updates. Based on an analysis from Sili Luo <rootlab@huawei.com>, where introducing a delay in the route lookup could cause a UAF on simultaneous sendmsg() and route deletion. Reported-by: Sili Luo <rootlab@huawei.com> Fixes: 889b7da23abf ("mctp: Add initial routing framework") Cc: stable@vger.kernel.org Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au> --- net/mctp/route.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-)