6.1-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 c64a0727f9b1cbc63a5538c8c0014e9a175ad864 ]
Prevent a dst ref loop on input in seg6_iptunnel.
Fixes: af4a2209b134 ("ipv6: sr: use dst_cache in seg6_input") Cc: David Lebrun dlebrun@google.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/seg6_iptunnel.c | 14 ++++++++++++-- 1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c index c161298c8b335..b186d85ec5b3f 100644 --- a/net/ipv6/seg6_iptunnel.c +++ b/net/ipv6/seg6_iptunnel.c @@ -472,10 +472,18 @@ static int seg6_input_core(struct net *net, struct sock *sk, { struct dst_entry *orig_dst = skb_dst(skb); struct dst_entry *dst = NULL; + struct lwtunnel_state *lwtst; struct seg6_lwt *slwt; int err;
- slwt = seg6_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; + + slwt = seg6_lwt_lwtunnel(lwtst);
local_bh_disable(); dst = dst_cache_get(&slwt->cache); @@ -490,7 +498,9 @@ static int seg6_input_core(struct net *net, struct sock *sk, 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(&slwt->cache, dst, &ipv6_hdr(skb)->saddr);