This is a note to let you know that I've just added the patch titled
net: ipv6: fix dst ref loops in rpl, seg6 and ioam6 lwtunnels
to the 6.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
net-ipv6-fix-dst-ref-loops-in-rpl-seg6-and-ioam6-lwt.patch
and it can be found in the queue-6.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 01157585e1e4aefbcfed1d8919812874a7afed8c
Author: Jakub Kicinski <kuba@xxxxxxxxxx>
Date: Wed Jan 29 19:15:19 2025 -0800
net: ipv6: fix dst ref loops in rpl, seg6 and ioam6 lwtunnels
[ Upstream commit 92191dd1073088753821b862b791dcc83e558e07 ]
Some lwtunnels have a dst cache for post-transformation dst.
If the packet destination did not change we may end up recording
a reference to the lwtunnel in its own cache, and the lwtunnel
state will never be freed.
Discovered by the ioam6.sh test, kmemleak was recently fixed
to catch per-cpu memory leaks. I'm not sure if rpl and seg6
can actually hit this, but in principle I don't see why not.
Fixes: 8cb3bf8bff3c ("ipv6: ioam: Add support for the ip6ip6 encapsulation")
Fixes: 6c8702c60b88 ("ipv6: sr: add support for SRH encapsulation and injection with lwtunnels")
Fixes: a7a29f9c361f ("net: ipv6: add rpl sr tunnel")
Reviewed-by: Simon Horman <horms@xxxxxxxxxx>
Link: https://patch.msgid.link/20250130031519.2716843-2-kuba@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/net/ipv6/ioam6_iptunnel.c b/net/ipv6/ioam6_iptunnel.c
index e81b45b1f6555..fb6cb540cd1bc 100644
--- a/net/ipv6/ioam6_iptunnel.c
+++ b/net/ipv6/ioam6_iptunnel.c
@@ -413,9 +413,12 @@ static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
goto drop;
}
- local_bh_disable();
- dst_cache_set_ip6(&ilwt->cache, cache_dst, &fl6.saddr);
- local_bh_enable();
+ /* cache only if we don't create a dst reference loop */
+ if (dst->lwtstate != cache_dst->lwtstate) {
+ local_bh_disable();
+ dst_cache_set_ip6(&ilwt->cache, cache_dst, &fl6.saddr);
+ local_bh_enable();
+ }
err = skb_cow_head(skb, LL_RESERVED_SPACE(cache_dst->dev));
if (unlikely(err))
diff --git a/net/ipv6/rpl_iptunnel.c b/net/ipv6/rpl_iptunnel.c
index 7ba22d2f2bfef..be084089ec783 100644
--- a/net/ipv6/rpl_iptunnel.c
+++ b/net/ipv6/rpl_iptunnel.c
@@ -236,9 +236,12 @@ static int rpl_output(struct net *net, struct sock *sk, struct sk_buff *skb)
goto drop;
}
- local_bh_disable();
- dst_cache_set_ip6(&rlwt->cache, dst, &fl6.saddr);
- local_bh_enable();
+ /* cache only if we don't create a dst reference loop */
+ if (orig_dst->lwtstate != dst->lwtstate) {
+ local_bh_disable();
+ dst_cache_set_ip6(&rlwt->cache, dst, &fl6.saddr);
+ local_bh_enable();
+ }
err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
if (unlikely(err))
diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c
index 4bf937bfc2633..316dbc2694f2a 100644
--- a/net/ipv6/seg6_iptunnel.c
+++ b/net/ipv6/seg6_iptunnel.c
@@ -575,9 +575,12 @@ static int seg6_output_core(struct net *net, struct sock *sk,
goto drop;
}
- local_bh_disable();
- dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr);
- local_bh_enable();
+ /* cache only if we don't create a dst reference loop */
+ if (orig_dst->lwtstate != dst->lwtstate) {
+ local_bh_disable();
+ dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr);
+ local_bh_enable();
+ }
err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
if (unlikely(err))
