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=1793211445; b=pkkxrd8ztsevpG0HWHcVTorcu77riafVhobMV8gDSjFzu3xLfTRO1eZENuZ5WIyGdJav XVLbzbVhiShHABoVH98jgBpaTMNtl5qnEYiimJ76FUFhSmwNa9Asri3R4HMwwBVfD9gWJ oDqt04vk9ozuFJEpmpdoiVlZaSQ62qnKT0ERjqkikF6Pr4aAqOo1/tPsHtJpilANjRcM+ xQ7Fyz+7vfdo8jiE6ZJ6MC0g2LWWL4fk9yWbhfBxkkKUzMmqaUK5hcQpicqdL80dn5POG gKD6rosastQ0wJkblu1RRJolvuYJ105rzTt9DJTan0aQh3gdQ/9zkW69juuOeuhmCCw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793211445; 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=1ASYBGKvX6e8DisISmN3YIxMJlkYRT51hgWb2jtZw2k=; b=IsD39nzPr+Bt5JVVa50yPXzsAgjAq0b7RR+NsUtt4qbfgbmkPDPX8AaqxqN6qVDdH10Y t012LB3Eu9Gslqan/sQTn1S44qSGcaLLGSqgp7U4FPXiUbt23mcKLe+8UZFm6oGROQZds Z66tarm9i6O1otCCnx3+XBOIUMO1XtF+htmeABN9G/ILMnUYUNZASOu5GESYC1A/xWbNK nBwe6bSgx7jNZYfsNyCYk7+gKCa70HsA6oh87koWX+btu9TswM21O6xuvOLEvg/8R9o1b tBr8F8YqZs5cXsnnXhL44f7RXa5zHFnGvY8LRNvl+hu5IJ2XeNy6B0Laz6CkRZjWPOA== 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=IypabGpT; 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 DB4C7606A31E; Wed, 28 Oct 2026 18:17:24 +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=IypabGpT Received: by smtp.kernel.org (Postfix) with ESMTPSA id 06A7D1F01825; Wed, 28 Oct 2026 18:17:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793211444; bh=1ASYBGKvX6e8DisISmN3YIxMJlkYRT51hgWb2jtZw2k=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=IypabGpTB7A4GWLnO1/XVFWWCF3H97n8E2BdNLyrQIV5aWRn1orAFEFM6MyoJR8Ur HvTQOJaBZJj00nNL/3P5bl0ApgKk/haqGdOvCMIZPILXJSYmABdPwNz7Kqjm3/8z89 RsVUGKP8CDWPeXlwQbaEIJ3U4LlT1QkdQy0S15/I= 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 5.15 381/571] Bluetooth: RFCOMM: Fix NULL tty_dev dereference in rfcomm_dev_shutdown Date: Wed, 28 Oct 2026 17:58:48 +0100 Message-ID: <20261028170017.052889190@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028170008.009143722@linuxfoundation.org> References: <20261028170008.009143722@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 5.15-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 */