From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9F95D4A35; Tue, 13 Oct 2026 12:40:06 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791895207; cv=none; b=pxd3A28v6Y/slG/RYdqSQdKMqdnCB1x3t67QgF8F72Lx5qgXQ6v+C50ZIMbAf2IN+gTYDgdJ/1RIlPwxUvhzoT5ZuslWcmIkUgR0osHHVUxp+yEs2PsoJRG8NZ7IZAmaHdDoX587ai+EcpqXJB6oB9kPX9rKUSLDHkosgd3eqLU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1791895207; c=relaxed/simple; bh=JXJ3Ksru6JJzJcli2cGESAvDDSnplGV2Lrok9ytXUvk=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=SbDJIfz01rJ+VRhGv1S3Fxxe/FV8zXTHvbVXhnNNxFA1QVVIs7TFRNDPACHkxh5Y1mYyMCLoIfG1ENe87e1UqDy9AZpyja3z2XUVpGaLlBfy739OMfahftQhITM+T6R8MVxSwZlFnsmosrQpQwwosZvNILe+E5RROUnO+l+iRxM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=tKxpIEuw; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="tKxpIEuw" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F30591F000FF; Tue, 13 Oct 2026 12:40:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1791895206; bh=GLaymcEPud+d46yXwkdVVMsl1hlbS+FaZ8NK+DmyOsg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=tKxpIEuwjM+kWR6gCAWqfVmqfpS/i8mKn3nv4RTbKOZ8bVVDqsZV2wqnZyImQhMhA 2Ff6Id5eY0O0zr5K2GW2sgUjWP7dlCE0YrjFWn1SzqM1bkOinXIfQmDE6Mo5ni7uEm g3u65ZEosjVCgs0G8W8xUC058/FjJ65o7SrO6PPI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chengfeng Ye , Luiz Augusto von Dentz Subject: [PATCH 6.12 180/497] Bluetooth: RFCOMM: Fix initial port reference race Date: Tue, 13 Oct 2026 13:35:47 +0200 Message-ID: <20261013112912.161771280@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261013112907.864180619@linuxfoundation.org> References: <20261013112907.864180619@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Chengfeng Ye commit 2d696c1ed3468dcb62578a3911e687110d463520 upstream. For RFCOMM_RELEASE_ONHUP devices, rfcomm_tty_install() and __rfcomm_release_dev() both use RFCOMM_TTY_OWNED to decide who drops the initial tty_port reference. The release path tests the bit separately from the install path setting it, so both can drop that reference. The synchronous hangup does not prevent this race: port->tty is not assigned until tty_port_open(), after installation. The following interleaving is possible: 1. Install and release each obtain a reference with rfcomm_dev_get(). 2. Release observes RFCOMM_TTY_OWNED clear. 3. Install sets RFCOMM_TTY_OWNED and drops the initial reference. 4. Release drops the same initial reference again. 5. TTY cleanup drops its reference and frees the device. 6. Release performs its final tty_port_put() on the freed port. KASAN reported: BUG: KASAN: slab-use-after-free in tty_port_put+0x22/0x190 Write of size 4 at addr ffff8881001d3d5c by task poc/92 Call Trace: tty_port_put+0x22/0x190 rfcomm_dev_ioctl+0x1d4/0x1930 sock_do_ioctl+0x110/0x260 sock_ioctl+0x380/0x590 __x64_sys_ioctl+0x134/0x1c0 Allocated by task 88: rfcomm_dev_ioctl+0x8f6/0x1930 sock_do_ioctl+0x110/0x260 sock_ioctl+0x380/0x590 __x64_sys_ioctl+0x134/0x1c0 Freed by task 65: kfree+0x131/0x3c0 rfcomm_dev_destruct+0x23b/0x2f0 release_one_tty+0xc1/0x370 process_one_work+0x661/0x1090 Use test_and_set_bit() in both paths so that only the caller that changes RFCOMM_TTY_OWNED from clear to set drops the initial reference. Each path keeps its own lookup reference until release or TTY cleanup, preserving the existing callback ordering and error handling. Fixes: 80ea73378af4 ("Bluetooth: Fix unreleased rfcomm_dev reference") Cc: stable@vger.kernel.org Assisted-by: LLM Signed-off-by: Chengfeng Ye Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Greg Kroah-Hartman --- net/bluetooth/rfcomm/tty.c | 7 +++---- 1 file changed, 3 insertions(+), 4 deletions(-) --- a/net/bluetooth/rfcomm/tty.c +++ b/net/bluetooth/rfcomm/tty.c @@ -465,7 +465,7 @@ static int __rfcomm_release_dev(void __u /* Shut down TTY synchronously before freeing rfcomm_dev */ tty_port_tty_vhangup(&dev->port); - if (!test_bit(RFCOMM_TTY_OWNED, &dev->status)) + if (!test_and_set_bit(RFCOMM_TTY_OWNED, &dev->status)) tty_port_put(&dev->port); tty_port_put(&dev->port); @@ -727,10 +727,9 @@ static int rfcomm_tty_install(struct tty * when the last process closes the tty. The behaviour is expected by * userspace. */ - if (test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags)) { - set_bit(RFCOMM_TTY_OWNED, &dev->status); + if (test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags) && + !test_and_set_bit(RFCOMM_TTY_OWNED, &dev->status)) tty_port_put(&dev->port); - } return 0; }