5.10-stable review patch. If anyone has any objections, please let me know.
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From: Justin Iurman justin.iurman@uliege.be
[ Upstream commit 13e55fbaec176119cff68a7e1693b251c8883c5f ]
Prevent a dst ref loop on input in rpl_iptunnel.
Fixes: a7a29f9c361f ("net: ipv6: add rpl sr tunnel") Cc: Alexander Aring alex.aring@gmail.com Cc: Ido Schimmel idosch@nvidia.com Reviewed-by: Ido Schimmel idosch@nvidia.com Signed-off-by: Justin Iurman justin.iurman@uliege.be Signed-off-by: Paolo Abeni pabeni@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- net/ipv6/rpl_iptunnel.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/net/ipv6/rpl_iptunnel.c b/net/ipv6/rpl_iptunnel.c index dbdfdd2e52784..95e84ec035203 100644 --- a/net/ipv6/rpl_iptunnel.c +++ b/net/ipv6/rpl_iptunnel.c @@ -259,10 +259,18 @@ static int rpl_input(struct sk_buff *skb) { struct dst_entry *orig_dst = skb_dst(skb); struct dst_entry *dst = NULL; + struct lwtunnel_state *lwtst; struct rpl_lwt *rlwt; int err;
- rlwt = rpl_lwt_lwtunnel(orig_dst->lwtstate); + /* We cannot dereference "orig_dst" once ip6_route_input() or + * skb_dst_drop() is called. However, in order to detect a dst loop, we + * need the address of its lwtstate. So, save the address of lwtstate + * now and use it later as a comparison. + */ + lwtst = orig_dst->lwtstate; + + rlwt = rpl_lwt_lwtunnel(lwtst);
local_bh_disable(); dst = dst_cache_get(&rlwt->cache); @@ -277,7 +285,9 @@ static int rpl_input(struct sk_buff *skb) if (!dst) { ip6_route_input(skb); dst = skb_dst(skb); - if (!dst->error) { + + /* cache only if we don't create a dst reference loop */ + if (!dst->error && lwtst != dst->lwtstate) { local_bh_disable(); dst_cache_set_ip6(&rlwt->cache, dst, &ipv6_hdr(skb)->saddr);