diff options
| author | Wei Wang <weiwan@google.com> | 2017-08-21 18:47:10 +0200 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2017-08-22 20:03:19 +0200 |
| commit | c5cff8561d2d0006e972bd114afd51f082fee77c (patch) | |
| tree | 590d33658f2a4a6add9db5734988b80a5313efc8 /net/ipv6/route.c | |
| parent | Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/klasse... (diff) | |
| download | linux-c5cff8561d2d0006e972bd114afd51f082fee77c.tar.xz linux-c5cff8561d2d0006e972bd114afd51f082fee77c.zip | |
ipv6: add rcu grace period before freeing fib6_node
We currently keep rt->rt6i_node pointing to the fib6_node for the route.
And some functions make use of this pointer to dereference the fib6_node
from rt structure, e.g. rt6_check(). However, as there is neither
refcount nor rcu taken when dereferencing rt->rt6i_node, it could
potentially cause crashes as rt->rt6i_node could be set to NULL by other
CPUs when doing a route deletion.
This patch introduces an rcu grace period before freeing fib6_node and
makes sure the functions that dereference it takes rcu_read_lock().
Note: there is no "Fixes" tag because this bug was there in a very
early stage.
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to '')
| -rw-r--r-- | net/ipv6/route.c | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/net/ipv6/route.c b/net/ipv6/route.c index 94d6a13d47f0..a9d3564caf49 100644 --- a/net/ipv6/route.c +++ b/net/ipv6/route.c @@ -1289,7 +1289,9 @@ static void rt6_dst_from_metrics_check(struct rt6_info *rt) static struct dst_entry *rt6_check(struct rt6_info *rt, u32 cookie) { - if (!rt->rt6i_node || (rt->rt6i_node->fn_sernum != cookie)) + u32 rt_cookie; + + if (!rt6_get_cookie_safe(rt, &rt_cookie) || rt_cookie != cookie) return NULL; if (rt6_check_expired(rt)) @@ -1357,8 +1359,14 @@ static void ip6_link_failure(struct sk_buff *skb) if (rt->rt6i_flags & RTF_CACHE) { if (dst_hold_safe(&rt->dst)) ip6_del_rt(rt); - } else if (rt->rt6i_node && (rt->rt6i_flags & RTF_DEFAULT)) { - rt->rt6i_node->fn_sernum = -1; + } else { + struct fib6_node *fn; + + rcu_read_lock(); + fn = rcu_dereference(rt->rt6i_node); + if (fn && (rt->rt6i_flags & RTF_DEFAULT)) + fn->fn_sernum = -1; + rcu_read_unlock(); } } } |