From 2fe40483ec257de2a0d819ef88e3e76c7e261319 Mon Sep 17 00:00:00 2001 From: Eric Dumazet Date: Fri, 31 May 2024 13:26:32 +0000 Subject: [PATCH] ipv6: ioam: block BH from ioam6_output() 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 Cc: Justin Iurman Acked-by: Paolo Abeni Link: https://lore.kernel.org/r/20240531132636.2637995-2-edumazet@google.com Signed-off-by: Jakub Kicinski --- 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 7563f8c6aa87..bf7120ecea1e 100644 --- a/net/ipv6/ioam6_iptunnel.c +++ b/net/ipv6/ioam6_iptunnel.c @@ -351,9 +351,9 @@ do_encap: 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 @@ do_encap: 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);