netdev - [PATCH net-next] ipv6: do not check fib6_has_expires() in fib6_info

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Date: Thu,  7 Dec 2023 20:13:22 +0000
From: Eric Dumazet <edumazet@...gle.com>
To: "David S . Miller" <davem@...emloft.net>, Jakub Kicinski <kuba@...nel.org>, 
	Paolo Abeni <pabeni@...hat.com>
Cc: David Ahern <dsahern@...nel.org>, netdev@...r.kernel.org, eric.dumazet@...il.com, 
	Eric Dumazet <edumazet@...gle.com>, syzbot+c15aa445274af8674f41@...kaller.appspotmail.com, 
	Kui-Feng Lee <thinker.li@...il.com>
Subject: [PATCH net-next] ipv6: do not check fib6_has_expires() in fib6_info_release()

My prior patch went a bit too far, because apparently fib6_has_expires()
could be true while f6i->gc_link is not hashed yet.

fib6_set_expires_locked() can indeed set RTF_EXPIRES
while f6i->fib6_table is NULL.

Original syzbot reports were about corruptions caused
by dangling f6i->gc_link.

Fixes: 5a08d0065a91 ("ipv6: add debug checks in fib6_info_release()")
Reported-by: syzbot+c15aa445274af8674f41@...kaller.appspotmail.com
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Cc: David Ahern <dsahern@...nel.org>
Cc: Kui-Feng Lee <thinker.li@...il.com>
---
 include/net/ip6_fib.h | 1 -
 1 file changed, 1 deletion(-)

diff --git a/include/net/ip6_fib.h b/include/net/ip6_fib.h
index e1e7a894863a7891610ce5afb2034473cc208d3e..95ed495c3a4028457baf1503c367d2e7a6e14770 100644
--- a/include/net/ip6_fib.h
+++ b/include/net/ip6_fib.h
@@ -329,7 +329,6 @@ static inline bool fib6_info_hold_safe(struct fib6_info *f6i)
 static inline void fib6_info_release(struct fib6_info *f6i)
 {
 	if (f6i && refcount_dec_and_test(&f6i->fib6_ref)) {
-		DEBUG_NET_WARN_ON_ONCE(fib6_has_expires(f6i));
 		DEBUG_NET_WARN_ON_ONCE(!hlist_unhashed(&f6i->gc_link));
 		call_rcu(&f6i->rcu, fib6_info_destroy_rcu);
 	}
-- 
2.43.0.472.g3155946c3a-goog