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net: ipv6: fix dst ref loop on input in seg6 lwt

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[ Upstream commit c64a0727f9b1cbc63a5538c8c0014e9a175ad864 ]

Prevent a dst ref loop on input in seg6_iptunnel.

Fixes: af4a2209b1 ("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>
This commit is contained in:
Justin Iurman 2025-02-25 18:51:38 +01:00 committed by Greg Kroah-Hartman
parent c447c5a9c4
commit 7f9aabbadf
1 changed files with 12 additions and 2 deletions
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14
net/ipv6/seg6_iptunnel.c
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@ -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);