[PATCH 4.3 10/71] ipv6: Check rt->dst.from for the DST_NOCACHE route

From: Greg Kroah-Hartman
Date: Sat Dec 12 2015 - 15:22:53 EST


4.3-stable review patch. If anyone has any objections, please let me know.

------------------

From: Martin KaFai Lau <kafai@xxxxxx>

[ 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@xxxxxx>
Cc: Hannes Frederic Sowa <hannes@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
include/net/ip6_fib.h | 3 ++-
net/ipv6/route.c | 3 ++-
2 files changed, 4 insertions(+), 2 deletions(-)

--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -167,7 +167,8 @@ static inline void rt6_update_expires(st

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;
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -1299,7 +1299,8 @@ static struct dst_entry *ip6_dst_check(s

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);


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/