ipv6: Check rt->dst.from for the DST_NOCACHE route

[ Upstrem commit 02bcf4e082e4dc634409a6a6cb7def8806d6e5e6 ]

All DST_NOCACHE rt6_info used to have rt->dst.from set to
its parent.

After commit 8e3d5be73681 ("ipv6: Avoid double dst_free"),
DST_NOCACHE is also set to rt6_info which does not have
a parent (i.e. rt->dst.from is NULL).

This patch catches the rt->dst.from == NULL case.

Fixes: 8e3d5be73681 ("ipv6: Avoid double dst_free")
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Cc: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index aaf9700fc9e5f8279a172a7ee447cf4f9b5b6ffe..fb961a576abe4a62d02c69d6393abd91a2930fe1 100644 (file)
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -167,7 +167,8 @@ static inline void rt6_update_expires(struct rt6_info *rt0, int timeout)
 
 static inline u32 rt6_get_cookie(const struct rt6_info *rt)
 {
-       if (rt->rt6i_flags & RTF_PCPU || unlikely(rt->dst.flags & DST_NOCACHE))
+       if (rt->rt6i_flags & RTF_PCPU ||
+           (unlikely(rt->dst.flags & DST_NOCACHE) && rt->dst.from))
                rt = (struct rt6_info *)(rt->dst.from);
 
        return rt->rt6i_node ? rt->rt6i_node->fn_sernum : 0;

diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index ea892c19a1ba1aa3bdbdf124251bf9ea6d6f6cf7..d3773269d6e045a83f54cf76f452622916fbc0aa 100644 (file)
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1299,7 +1299,8 @@ static struct dst_entry *ip6_dst_check(struct dst_entry *dst, u32 cookie)
 
        rt6_dst_from_metrics_check(rt);
 
-       if ((rt->rt6i_flags & RTF_PCPU) || unlikely(dst->flags & DST_NOCACHE))
+       if (rt->rt6i_flags & RTF_PCPU ||
+           (unlikely(dst->flags & DST_NOCACHE) && rt->dst.from))
                return rt6_dst_from_check(rt, cookie);
        else
                return rt6_check(rt, cookie);