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net: ipv6: fix dst ref loops in rpl, seg6 and ioam6 lwtunnels

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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: 8cb3bf8bff ("ipv6: ioam: Add support for the ip6ip6 encapsulation")
Fixes: 6c8702c60b ("ipv6: sr: add support for SRH encapsulation and injection with lwtunnels")
Fixes: a7a29f9c36 ("net: ipv6: add rpl sr tunnel")
Reviewed-by: Simon Horman <horms@kernel.org>
Link: https://patch.msgid.link/20250130031519.2716843-2-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski 2025-01-29 19:15:19 -08:00
parent c71a192976
commit 92191dd107
3 changed files with 18 additions and 9 deletions
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9
net/ipv6/ioam6_iptunnel.c
View file

@ -410,9 +410,12 @@ do_encap:
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))

9
net/ipv6/rpl_iptunnel.c
View file

@ -235,9 +235,12 @@ 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))

9
net/ipv6/seg6_iptunnel.c
View file

@ -576,9 +576,12 @@ 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))