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ipv6: ioam: block BH from ioam6_output()

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As explained in commit 1378817486 ("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: 8cb3bf8bff ("ipv6: ioam: Add support for the ip6ip6 encapsulation")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Justin Iurman <justin.iurman@uliege.be>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Link: https://lore.kernel.org/r/20240531132636.2637995-2-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Eric Dumazet 2024-05-31 13:26:32 +00:00 committed by Jakub Kicinski
parent ffbe335b8d
commit 2fe40483ec
1 changed files with 4 additions and 4 deletions
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8
net/ipv6/ioam6_iptunnel.c
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@ -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);