From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793209077; b=U349Snj8gtlrzNpiIrnBScSS0e5No3YchR1XMq+Wx3KMHJ9B9/mmsQmJhzQ5C7oF+Q7u CGOugODb7wKvbwYhE7dGhGm4fg37KpNmWNigGEuGz4adsYbfWbxpbGb2AInOEBOLiRZCn xedtRKPKFT8AbZwV8ZbcqVmwzil5EzW3y5WgRcaDjp9OpoABcpcK/QrFUt2I/G+D8PMKN V54MVq9mTuKNFsmOMloR49SH6saCe2cVvB5TJoGuHxc5q8BO5oodO/FO3YEOIwGMJrEIK cbOdn5zJAJSilggpGhoPOv+MnUY9TA87XC1ozMp9W5AmIL75jaIAKiBLFmuhljo3lxg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793209077; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=uIp++ceshqdUke8FEissGPIGLNKVQe5ViQwURPXo3cg=; b=J++gMzyI/6oJ119oxgGHfq4HA4nEqCajXCFNdAguwDmYk34vS3Dv9dasLG9hg/ElbN98 1v9LCpgv4o18M1omEAJas/fv7FHbvRtL8eN6D7RwhNXGoDuppKFruyj/Po8rYQrMXnBVy zPzjUPw6hcN1Y8oewSdS5WgjPlk1LJhypOxQLrsTKN/i9b283Pb/segugdObqpacCGAX0 txW2ZlKFeL2dv1cRXJJT1h2JRCnqZlJ30Jj5MPPmbQ7zkRv8Ic1RW5B8ZRCSC2IbKnboF jkBI1QaSP0JdzGIL9CGzAY8Q9x15TTDtab+3M8vwGBsRJfxnaGMgqi4Y/2pbTlbg+0Q== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b="u5kva/OB"; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B99AA606A335; Wed, 28 Oct 2026 17:37:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=u5kva/OB Received: by smtp.kernel.org (Postfix) with ESMTPSA id 155B91F01825; Wed, 28 Oct 2026 17:37:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793209076; bh=uIp++ceshqdUke8FEissGPIGLNKVQe5ViQwURPXo3cg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=u5kva/OBzLuicuaFsyhqqb55zIeUr/0HBXlHyvcYUoUDZn6Lcy9SL6IxN8SBd3q0V Z9AOQ1MlcsaYJ/k1n4wsc1eY152iEGoltaZIYj7QMbXW0j68WlJ7hSXwJNAXNY81zs Jy2wLXUMBQJ5HXnSHDbJIo2IfQPce9bwkpTvW7K8= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot+4a807caf7680652d53b6@syzkaller.appspotmail.com, Palla Raghunath , Luiz Augusto von Dentz Subject: [PATCH 5.10 345/516] Bluetooth: RFCOMM: Fix NULL tty_dev dereference in rfcomm_dev_shutdown Date: Wed, 28 Oct 2026 17:58:17 +0100 Message-ID: <20261028170011.660295528@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170003.522232767@linuxfoundation.org> References: <20261028170003.522232767@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: Palla Raghunath commit 08e90633377f1b2567ab5ad6810b74c552246a07 upstream. syzbot hit a NULL pointer dereference in rfcomm_dev_shutdown() when an RFCOMM tty is closed. rfcomm_dev_add() puts the new device on rfcomm_dev_list first and only then registers the tty device and saves it in dev->tty_dev. If that registration fails, dev->tty_dev is never set at all. The device can be looked up in the meantime, so an open() of /dev/rfcommN gets through rfcomm_tty_install() and attaches to it. When that tty is closed again, rfcomm_dev_shutdown() uses dev->tty_dev without checking it: Oops: general protection fault, probably for non-canonical address KASAN: null-ptr-deref in range [0x0000000000000040-0x0000000000000047] RIP: 0010:rfcomm_dev_shutdown+0x48/0xb0 net/bluetooth/rfcomm/tty.c:131 Call Trace: tty_port_shutdown+0x1bf/0x220 drivers/tty/tty_port.c:372 tty_port_close+0x4e/0x150 drivers/tty/tty_port.c:705 tty_release+0x359/0x1670 drivers/tty/tty_io.c:1718 __fput+0x418/0xa50 fs/file_table.c:512 rfcomm_dev_destruct() already copes with a NULL dev->tty_dev. Add the same check to rfcomm_dev_shutdown(), so the tty device is only moved when it was actually registered. Fixes: cad348a17e17 ("Bluetooth: Implement .activate, .shutdown and .carrier_raised methods") Reported-by: syzbot+4a807caf7680652d53b6@syzkaller.appspotmail.com Closes: https://syzkaller.appspot.com/bug?extid=4a807caf7680652d53b6 Cc: stable@vger.kernel.org Signed-off-by: Palla Raghunath Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Greg Kroah-Hartman --- net/bluetooth/rfcomm/tty.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/net/bluetooth/rfcomm/tty.c +++ b/net/bluetooth/rfcomm/tty.c @@ -132,7 +132,7 @@ static void rfcomm_dev_shutdown(struct t { struct rfcomm_dev *dev = container_of(port, struct rfcomm_dev, port); - if (dev->tty_dev->parent) + if (dev->tty_dev && dev->tty_dev->parent) device_move(dev->tty_dev, NULL, DPM_ORDER_DEV_LAST); /* close the dlc */