6.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Eric Dumazet <edumazet@xxxxxxxxxx>
[ Upstream commit 2fe40483ec257de2a0d819ef88e3e76c7e261319 ]
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 ioam6_output() is not good enough,
because ioam6_output() is called from process context,
lwtunnel_output() only uses rcu_read_lock().
We might be interrupted by a softirq, re-enter ioam6_output()
and corrupt dst_cache data structures.
Fix the race by using local_bh_disable() instead of
preempt_disable().
Fixes: 8cb3bf8bff3c ("ipv6: ioam: Add support for the ip6ip6 encapsulation")
Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Cc: Justin Iurman <justin.iurman@xxxxxxxxx>
Acked-by: Paolo Abeni <pabeni@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20240531132636.2637995-2-edumazet@xxxxxxxxxx
Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
net/ipv6/ioam6_iptunnel.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/net/ipv6/ioam6_iptunnel.c b/net/ipv6/ioam6_iptunnel.c
index 7563f8c6aa87c..bf7120ecea1eb 100644
--- a/net/ipv6/ioam6_iptunnel.c
+++ b/net/ipv6/ioam6_iptunnel.c
@@ -351,9 +351,9 @@ static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
goto drop;
if (!ipv6_addr_equal(&orig_daddr, &ipv6_hdr(skb)->daddr)) {
- preempt_disable();
+ local_bh_disable();
dst = dst_cache_get(&ilwt->cache);
- preempt_enable();
+ local_bh_enable();
if (unlikely(!dst)) {
struct ipv6hdr *hdr = ipv6_hdr(skb);
@@ -373,9 +373,9 @@ static int ioam6_output(struct net *net, struct sock *sk, struct sk_buff *skb)
goto drop;
}
- preempt_disable();
+ local_bh_disable();
dst_cache_set_ip6(&ilwt->cache, dst, &fl6.saddr);
- preempt_enable();
+ local_bh_enable();
}
skb_dst_drop(skb);
--
2.43.0
