netdev - [PATCH RESEND] tipc: fix RCU dereference race in tipc_aead_users

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Message-ID: <20260203145621.17399-1-git@danielhodges.dev>
Date: Tue,  3 Feb 2026 09:56:21 -0500
From: Daniel Hodges <git@...ielhodges.dev>
To: jmaloy@...hat.com,
	davem@...emloft.net,
	edumazet@...gle.com,
	kuba@...nel.org,
	pabeni@...hat.com
Cc: horms@...nel.org,
	ying.xue@...driver.com,
	tuong.t.lien@...tech.com.au,
	netdev@...r.kernel.org,
	tipc-discussion@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org,
	Daniel Hodges <hodgesd@...a.com>,
	stable@...r.kernel.org
Subject: [PATCH RESEND] tipc: fix RCU dereference race in tipc_aead_users_dec()

From: Daniel Hodges <hodgesd@...a.com>

tipc_aead_users_dec() calls rcu_dereference(aead) twice: once to store
in 'tmp' for the NULL check, and again inside the atomic_add_unless()
call.

Use the already-dereferenced 'tmp' pointer consistently, matching the
correct pattern used in tipc_aead_users_inc() and tipc_aead_users_set().

Fixes: fc1b6d6de220 ("tipc: introduce TIPC encryption & authentication")
Cc: stable@...r.kernel.org
Reviewed-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Daniel Hodges <hodgesd@...a.com>
---
 net/tipc/crypto.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c
index 970db62bd029..a3f9ca28c3d5 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -460,7 +460,7 @@ static void tipc_aead_users_dec(struct tipc_aead __rcu *aead, int lim)
 	rcu_read_lock();
 	tmp = rcu_dereference(aead);
 	if (tmp)
-		atomic_add_unless(&rcu_dereference(aead)->users, -1, lim);
+		atomic_add_unless(&tmp->users, -1, lim);
 	rcu_read_unlock();
 }
 
-- 
2.52.0