diff options
author | Martin KaFai Lau <kafai@fb.com> | 2019-04-30 20:45:12 +0300 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2019-05-02 00:17:54 +0300 |
commit | 886b7a50100a50f1cbd08a6f8ec5884dfbe082dc (patch) | |
tree | f18e97f6f5ac9054af65539f00e52c6160470a20 /net/ipv6 | |
parent | f3505745c07ff50c22aeca9dde98762d1c8b5898 (diff) | |
download | linux-886b7a50100a50f1cbd08a6f8ec5884dfbe082dc.tar.xz |
ipv6: A few fixes on dereferencing rt->from
It is a followup after the fix in
commit 9c69a1320515 ("route: Avoid crash from dereferencing NULL rt->from")
rt6_do_redirect():
1. NULL checking is needed on rt->from because a parallel
fib6_info delete could happen that sets rt->from to NULL.
(e.g. rt6_remove_exception() and fib6_drop_pcpu_from()).
2. fib6_info_hold() is not enough. Same reason as (1).
Meaning, holding dst->__refcnt cannot ensure
rt->from is not NULL or rt->from->fib6_ref is not 0.
Instead of using fib6_info_hold_safe() which ip6_rt_cache_alloc()
is already doing, this patch chooses to extend the rcu section
to keep "from" dereference-able after checking for NULL.
inet6_rtm_getroute():
1. NULL checking is also needed on rt->from for a similar reason.
Note that inet6_rtm_getroute() is using RTNL_FLAG_DOIT_UNLOCKED.
Fixes: a68886a69180 ("net/ipv6: Make from in rt6_info rcu protected")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Wei Wang <weiwan@google.com>
Reviewed-by: David Ahern <dsahern@gmail.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/ipv6')
-rw-r--r-- | net/ipv6/route.c | 38 |
1 files changed, 18 insertions, 20 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 2cc166bc978d..0520aca3354b 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -3392,11 +3392,8 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu rcu_read_lock(); from = rcu_dereference(rt->from); - /* This fib6_info_hold() is safe here because we hold reference to rt - * and rt already holds reference to fib6_info. - */ - fib6_info_hold(from); - rcu_read_unlock(); + if (!from) + goto out; nrt = ip6_rt_cache_alloc(from, &msg->dest, NULL); if (!nrt) @@ -3408,10 +3405,7 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu nrt->rt6i_gateway = *(struct in6_addr *)neigh->primary_key; - /* No need to remove rt from the exception table if rt is - * a cached route because rt6_insert_exception() will - * takes care of it - */ + /* rt6_insert_exception() will take care of duplicated exceptions */ if (rt6_insert_exception(nrt, from)) { dst_release_immediate(&nrt->dst); goto out; @@ -3424,7 +3418,7 @@ static void rt6_do_redirect(struct dst_entry *dst, struct sock *sk, struct sk_bu call_netevent_notifiers(NETEVENT_REDIRECT, &netevent); out: - fib6_info_release(from); + rcu_read_unlock(); neigh_release(neigh); } @@ -5023,16 +5017,20 @@ static int inet6_rtm_getroute(struct sk_buff *in_skb, struct nlmsghdr *nlh, rcu_read_lock(); from = rcu_dereference(rt->from); - - if (fibmatch) - err = rt6_fill_node(net, skb, from, NULL, NULL, NULL, iif, - RTM_NEWROUTE, NETLINK_CB(in_skb).portid, - nlh->nlmsg_seq, 0); - else - err = rt6_fill_node(net, skb, from, dst, &fl6.daddr, - &fl6.saddr, iif, RTM_NEWROUTE, - NETLINK_CB(in_skb).portid, nlh->nlmsg_seq, - 0); + if (from) { + if (fibmatch) + err = rt6_fill_node(net, skb, from, NULL, NULL, NULL, + iif, RTM_NEWROUTE, + NETLINK_CB(in_skb).portid, + nlh->nlmsg_seq, 0); + else + err = rt6_fill_node(net, skb, from, dst, &fl6.daddr, + &fl6.saddr, iif, RTM_NEWROUTE, + NETLINK_CB(in_skb).portid, + nlh->nlmsg_seq, 0); + } else { + err = -ENETUNREACH; + } rcu_read_unlock(); if (err < 0) { |