4.19-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit c0b98ac1cc104f48763cdb27b1e9ac25fd81fc90 ]
As explained in commit 1378817486d6 ("tipc: block BH
before using dst_cache"), net/core/dst_cache.c
helpers need to be called with BH disabled.
Disabling preemption in seg6_output_core() is not good enough,
because seg6_output_core() is called from process context,
lwtunnel_output() only uses rcu_read_lock().
We might be interrupted by a softirq, re-enter seg6_output_core()
and corrupt dst_cache data structures.
Fix the race by using local_bh_disable() instead of
preempt_disable().
Apply a similar change in seg6_input_core().
Fixes: fa79581ea66c ("ipv6: sr: fix several BUGs when preemption is enabled")
Fixes: 6c8702c60b88 ("ipv6: sr: add support for SRH encapsulation and injection with lwtunnels")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: David Lebrun <dlebrun@xxxxxxxxxx>
Acked-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240531132636.2637995-4-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/ipv6/seg6_iptunnel.c | 14 ++++++--------
1 file changed, 6 insertions(+), 8 deletions(-)
diff --git a/net/ipv6/seg6_iptunnel.c b/net/ipv6/seg6_iptunnel.c
index 2e90672852c86..7dc447e08a486 100644
--- a/net/ipv6/seg6_iptunnel.c
+++ b/net/ipv6/seg6_iptunnel.c
@@ -313,9 +313,8 @@ static int seg6_input(struct sk_buff *skb)
slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
- preempt_disable();
+ local_bh_disable();
dst = dst_cache_get(&slwt->cache);
- preempt_enable();
skb_dst_drop(skb);
@@ -323,14 +322,13 @@ static int seg6_input(struct sk_buff *skb)
ip6_route_input(skb);
dst = skb_dst(skb);
if (!dst->error) {
- preempt_disable();
dst_cache_set_ip6(&slwt->cache, dst,
&ipv6_hdr(skb)->saddr);
- preempt_enable();
}
} else {
skb_dst_set(skb, dst);
}
+ local_bh_enable();
err = skb_cow_head(skb, LL_RESERVED_SPACE(dst->dev));
if (unlikely(err))
@@ -352,9 +350,9 @@ static int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
slwt = seg6_lwt_lwtunnel(orig_dst->lwtstate);
- preempt_disable();
+ local_bh_disable();
dst = dst_cache_get(&slwt->cache);
- preempt_enable();
+ local_bh_enable();
if (unlikely(!dst)) {
struct ipv6hdr *hdr = ipv6_hdr(skb);
@@ -374,9 +372,9 @@ static int seg6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
goto drop;
}
- preempt_disable();
+ local_bh_disable();
dst_cache_set_ip6(&slwt->cache, dst, &fl6.saddr);
- preempt_enable();
+ local_bh_enable();
}
skb_dst_drop(skb);
--
2.43.0
