From nobody Fri Oct 2 13:04:17 2026 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 EA91B3C3F45; Fri, 31 Jul 2026 08:06:30 +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=1785485192; cv=none; b=Kq7NBsB3U778uI84K3P6QiTOkp3qvD8Pu/vFe6rJvGVSq5jEfA48/vKPyFNSkzG3kFhFOpBtU5cLxetG0qTlYm0JdEwII66S8mHsLPdMHPWNmQFb1hOUMS9/I0i23RoJPcxD9oWFMscYh6JXuGFpVtD1fXTX9cDZEGQ2th9l5m8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785485192; c=relaxed/simple; bh=qdq5EyXtVwNpuw7AVa2YqUJsxXL4T/jgAWUgunTxXbc=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=a7fINy7oDi3ocjmM2upjZPkzmH9/cg2N67G+ySDUICY9Zg7mndlZG1pouKiM/nO/grmCsn2gr8II3luiDtmicP8u3J7z+aj6yQQZVTNyCZAq07TWJWTS8ptpJ2P+UM1ex4L6f0OxaAANiBp2XDYZVCE64j/JKhRUlpTLS7jbUy0= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=yBIfDb02; 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="yBIfDb02" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 34C3C1F000E9; Fri, 31 Jul 2026 08:06:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785485190; bh=IDKBP4xS0/qjx/ftnPDgwoOfm5XHHxPnCxJvToAEpTI=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=yBIfDb02v4bCOjwHHdpQ37TI+V5fYLEMpGu2W31us6rsffwm4gaJYeEKLmmRK7dSu HKY1rK9oDcY8K7FWBJMUK8LRxPsx1Bgo2XHATFwZ70V1Q+A0Jr2ruWtNpcD7OWjNGb KadN+wzf6TuIkKj6na5V7o1lwBmSmc8ftBX15pUI= From: Greg Kroah-Hartman Date: Fri, 31 Jul 2026 10:06:09 +0200 Subject: [PATCH 1/2] serdev: fix race between tty-port unregister and in-flight callbacks Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260731-aisle-tty-serdev-v1-1-2401a3189327@linuxfoundation.org> References: <20260731-aisle-tty-serdev-v1-0-2401a3189327@linuxfoundation.org> In-Reply-To: <20260731-aisle-tty-serdev-v1-0-2401a3189327@linuxfoundation.org> To: Markus Probst , linux-serial@vger.kernel.org Cc: Rob Herring , Jiri Slaby , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Joshua Rogers , stable X-Mailer: b4 0.16-dev-401aa X-Developer-Signature: v=1; a=openpgp-sha256; l=2153; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=sWQEFy8Ddd2hU898EwQf6RGWycJhOwdR3kEU9oW/Jds=; b=owGbwMvMwCRo6H6F97bub03G02pJDFk54aXPWA89SVNrOR6dcSD9cvU/66PnTbkObjiiflBV4 9+SJaLrO2JZGASZGGTFFFm+bOM5ur/ikKKXoe1pmDmsTCBDGLg4BWAispcZ5lk5t8uxX6jbWC4m 4/q9tIcnY8cRLYYFE74v23zwp0qofCbn09ufO1ilPBYyAQA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 From: Joshua Rogers serdev_tty_port_unregister() clears port->client_data and frees the controller without synchronizing with in-flight flip buffer work. This can cause NULL pointer dereferences or use-after-free if ttyport_receive_buf() or ttyport_write_wakeup() runs concurrently. Add cancel_work_sync() to drain pending buffer work before clearing state, and add NULL checks for client_data in both callbacks as secondary hardening. Assisted-by: AISLE:Snapshot Cc: stable Signed-off-by: Joshua Rogers Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serdev/serdev-ttyport.c | 15 +++++++++++++-- 1 file changed, 13 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serde= v-ttyport.c index bab1b143b8a6..48ce5b3f8308 100644 --- a/drivers/tty/serdev/serdev-ttyport.c +++ b/drivers/tty/serdev/serdev-ttyport.c @@ -26,9 +26,14 @@ static size_t ttyport_receive_buf(struct tty_port *port,= const u8 *cp, const u8 *fp, size_t count) { struct serdev_controller *ctrl =3D port->client_data; - struct serport *serport =3D serdev_controller_get_drvdata(ctrl); + struct serport *serport; size_t ret; =20 + if (!ctrl) + return 0; + + serport =3D serdev_controller_get_drvdata(ctrl); + if (!test_bit(SERPORT_ACTIVE, &serport->flags)) return 0; =20 @@ -46,9 +51,14 @@ static size_t ttyport_receive_buf(struct tty_port *port,= const u8 *cp, static void ttyport_write_wakeup(struct tty_port *port) { struct serdev_controller *ctrl =3D port->client_data; - struct serport *serport =3D serdev_controller_get_drvdata(ctrl); + struct serport *serport; struct tty_struct *tty; =20 + if (!ctrl) + return; + + serport =3D serdev_controller_get_drvdata(ctrl); + tty =3D tty_port_tty_get(port); if (!tty) return; @@ -312,6 +322,7 @@ int serdev_tty_port_unregister(struct tty_port *port) return -ENODEV; =20 serdev_controller_remove(ctrl); + cancel_work_sync(&port->buf.work); port->client_data =3D NULL; port->client_ops =3D &tty_port_default_client_ops; serdev_controller_put(ctrl); --=20 2.55.0 From nobody Fri Oct 2 13:04:17 2026 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 F337B3CA491; Fri, 31 Jul 2026 08:06:33 +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; 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Fri, 31 Jul 2026 08:06:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1785485193; bh=kWtYNBXgx1ERnjuPzRf0p7LW+RSZjWnKR1InaA5DbMU=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=YNZxXxdPuUa8QYFJYecg20/DzUICGSXsOM3OK3CBujNOpH9wCPVnZeveBbVI7ip+M 9G+lcDYptuzH6dH2TOFgAWJ9v4Or6906TErwgQFO1OmIBD8lwLoJiKwg1iblfc+BbZ Ak/cWzyf1CjHSZWtfR+tfc6G5HDoISvGN51pyWCQ= From: Greg Kroah-Hartman Date: Fri, 31 Jul 2026 10:06:10 +0200 Subject: [PATCH 2/2] serdev: use tty_port_tty_get() in ttyport_write_buf() to prevent UAF Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20260731-aisle-tty-serdev-v1-2-2401a3189327@linuxfoundation.org> References: <20260731-aisle-tty-serdev-v1-0-2401a3189327@linuxfoundation.org> In-Reply-To: <20260731-aisle-tty-serdev-v1-0-2401a3189327@linuxfoundation.org> To: Markus Probst , linux-serial@vger.kernel.org Cc: Rob Herring , Jiri Slaby , linux-kernel@vger.kernel.org, Greg Kroah-Hartman , Joshua Rogers , stable X-Mailer: b4 0.16-dev-401aa X-Developer-Signature: v=1; a=openpgp-sha256; l=1578; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=CIoA1U7goq1GlxfkNWw/iYNPnQOup6iGI8gPBqnZteU=; b=owGbwMvMwCRo6H6F97bub03G02pJDFk54aWGJ9vMRZMubW2rVfIwmz5tMeesuM656qqN/797P PxUNdWgI5aFQZCJQVZMkeXLNp6j+ysOKXoZ2p6GmcPKBDKEgYtTACZiLs8w32frovxLqQfTnvT9 t/J8V5y87dc+b4YFRxa8lp5vOW/z43eBC5zEb9ce2XZiOgA= X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 From: Joshua Rogers ttyport_write_buf() snapshots serport->tty as a raw pointer without taking a reference, while ttyport_close() can concurrently release the tty via tty_release_struct(), leading to a use-after-free. Use tty_port_tty_get() to obtain a reference-counted tty pointer, matching the pattern already used by ttyport_write_wakeup(). Assisted-by: AISLE:Snapshot Cc: stable Signed-off-by: Joshua Rogers Signed-off-by: Greg Kroah-Hartman Reviewed-by: Markus Probst --- drivers/tty/serdev/serdev-ttyport.c | 12 ++++++++++-- 1 file changed, 10 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serdev/serdev-ttyport.c b/drivers/tty/serdev/serde= v-ttyport.c index 48ce5b3f8308..4d37c8130dd7 100644 --- a/drivers/tty/serdev/serdev-ttyport.c +++ b/drivers/tty/serdev/serdev-ttyport.c @@ -85,13 +85,21 @@ static const struct tty_port_client_operations client_o= ps =3D { static ssize_t ttyport_write_buf(struct serdev_controller *ctrl, const u8 = *data, size_t len) { struct serport *serport =3D serdev_controller_get_drvdata(ctrl); - struct tty_struct *tty =3D serport->tty; + struct tty_struct *tty; + ssize_t ret; =20 if (!test_bit(SERPORT_ACTIVE, &serport->flags)) return 0; =20 + tty =3D tty_port_tty_get(serport->port); + if (!tty) + return 0; + set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); - return tty->ops->write(serport->tty, data, len); + ret =3D tty->ops->write(tty, data, len); + tty_kref_put(tty); + + return ret; } =20 static void ttyport_write_flush(struct serdev_controller *ctrl) --=20 2.55.0