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([187.13.30.172]) by smtp.gmail.com with ESMTPSA id ada2fe7eead31-7b39b9ae253sm3267723137.8.2026.09.26.14.20.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 26 Sep 2026 14:20:56 -0700 (PDT) From: Aldo Ariel Panzardo To: david@ixit.cz, davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com Cc: horms@kernel.org, oe-linux-nfc@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Aldo Ariel Panzardo Subject: [PATCH] nfc: llcp: clear device pointer on disconnect Date: Sat, 26 Sep 2026 18:20:41 -0300 Message-ID: <20260926212041.1342558-1-qwe.aldo@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit nfc_llcp_recv_disc() drops the device reference via nfc_put_device() when a connected socket receives a DISC PDU, but does not clear llcp_sock->dev. If the socket is later reconnected, any cleanup code that checks llcp_sock->dev will find a non-NULL pointer and attempt a second nfc_put_device(), underflowing the device refcount. Clear the pointer immediately after the put so that a subsequent reconnect does not double-release the device. Fixes: d646960f7986 ("NFC: Initial LLCP support") Cc: stable@vger.kernel.org Signed-off-by: Aldo Ariel Panzardo --- net/nfc/llcp_core.c | 1 + 1 file changed, 1 insertion(+) diff --git a/net/nfc/llcp_core.c b/net/nfc/llcp_core.c index 74bf81700..199543c47 100644 --- a/net/nfc/llcp_core.c +++ b/net/nfc/llcp_core.c @@ -1220,6 +1220,7 @@ static void nfc_llcp_recv_disc(struct nfc_llcp_local *local, if (sk->sk_state == LLCP_CONNECTED) { nfc_put_device(local->dev); + llcp_sock->dev = NULL; sk->sk_state = LLCP_CLOSED; sk->sk_state_change(sk); } -- 2.43.0