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[34.104.240.5]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-87c31ee8fc5sm458535b3a.9.2026.09.22.01.09.12 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Tue, 22 Sep 2026 01:09:14 -0700 (PDT) From: Ginger Li To: jmaloy@redhat.com, tung.quang.nguyen@est.tech Cc: netdev@vger.kernel.org, tipc-discussion@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: [PATCH net] tipc: Fix a data race on mon->peer_cnt in mon_timeout() Date: Tue, 22 Sep 2026 16:09:09 +0800 Message-ID: <20260922080909.21123-1-ginger.jzllee@gmail.com> X-Mailer: git-send-email 2.46.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit mon_timeout() evaluates dom_size(mon->peer_cnt) before it takes mon->lock, while mon->peer_cnt is updated under that lock by tipc_mon_add_peer() and tipc_mon_remove_peer(). The value can therefore be stale, and the decision whether the local domain has to be recomputed can be based on an outdated member count. Read mon->peer_cnt inside the write_lock_bh(&mon->lock) protected region. Fixes: 35c55c9877f8 ("tipc: add neighbor monitoring framework") Signed-off-by: Ginger Li --- net/tipc/monitor.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/tipc/monitor.c b/net/tipc/monitor.c --- a/net/tipc/monitor.c +++ b/net/tipc/monitor.c @@ -632,9 +632,10 @@ static void mon_timeout(struct timer_list *t) { struct tipc_monitor *mon = timer_container_of(mon, t, timer); struct tipc_peer *self; - int best_member_cnt = dom_size(mon->peer_cnt) - 1; + int best_member_cnt; write_lock_bh(&mon->lock); + best_member_cnt = dom_size(mon->peer_cnt) - 1; self = mon->self; if (self && (best_member_cnt != self->applied)) { mon_update_local_domain(mon); -- 2.43.0