From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 81AB5847A for ; Wed, 1 Mar 2023 18:10:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D4FCAC4339B; Wed, 1 Mar 2023 18:10:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1677694222; bh=3bJJUefTITWpBCvRbyEg2Sg7fd5UWN1/TEoNElIgvP8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WeBgS4sfUqc3KD5SQsMtpObcaRhKO9xv8rnuRal4i8Hpo3plw1jOYGmdpkRvGNFKr NiezvxA62AzqcDipFik2J7Q+/99OGuAFf5gzBBJnC14MQBoTLhFaMFqnCxVDRp0BG/ 5KzpTxZoWg0dmLOeESxCm5lZapSz0IxhARH81t9M= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, stable , Prashanth K , Alan Stern Subject: [PATCH 5.10 18/19] usb: gadget: u_serial: Add null pointer check in gserial_resume Date: Wed, 1 Mar 2023 19:08:47 +0100 Message-Id: <20230301180653.069435447@linuxfoundation.org> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20230301180652.316428563@linuxfoundation.org> References: <20230301180652.316428563@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Prashanth K commit 5ec63fdbca604568890c577753c6f66c5b3ef0b5 upstream. Consider a case where gserial_disconnect has already cleared gser->ioport. And if a wakeup interrupt triggers afterwards, gserial_resume gets called, which will lead to accessing of gser->ioport and thus causing null pointer dereference.Add a null pointer check to prevent this. Added a static spinlock to prevent gser->ioport from becoming null after the newly added check. Fixes: aba3a8d01d62 ("usb: gadget: u_serial: add suspend resume callbacks") Cc: stable Signed-off-by: Prashanth K Acked-by: Alan Stern Link: https://lore.kernel.org/r/1676309438-14922-1-git-send-email-quic_prashk@quicinc.com Signed-off-by: Greg Kroah-Hartman --- drivers/usb/gadget/function/u_serial.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-) --- a/drivers/usb/gadget/function/u_serial.c +++ b/drivers/usb/gadget/function/u_serial.c @@ -81,6 +81,9 @@ #define WRITE_BUF_SIZE 8192 /* TX only */ #define GS_CONSOLE_BUF_SIZE 8192 +/* Prevents race conditions while accessing gser->ioport */ +static DEFINE_SPINLOCK(serial_port_lock); + /* console info */ struct gs_console { struct console console; @@ -1376,8 +1379,10 @@ void gserial_disconnect(struct gserial * if (!port) return; + spin_lock_irqsave(&serial_port_lock, flags); + /* tell the TTY glue not to do I/O here any more */ - spin_lock_irqsave(&port->port_lock, flags); + spin_lock(&port->port_lock); gs_console_disconnect(port); @@ -1392,7 +1397,8 @@ void gserial_disconnect(struct gserial * tty_hangup(port->port.tty); } port->suspended = false; - spin_unlock_irqrestore(&port->port_lock, flags); + spin_unlock(&port->port_lock); + spin_unlock_irqrestore(&serial_port_lock, flags); /* disable endpoints, aborting down any active I/O */ usb_ep_disable(gser->out); @@ -1426,10 +1432,19 @@ EXPORT_SYMBOL_GPL(gserial_suspend); void gserial_resume(struct gserial *gser) { - struct gs_port *port = gser->ioport; + struct gs_port *port; unsigned long flags; - spin_lock_irqsave(&port->port_lock, flags); + spin_lock_irqsave(&serial_port_lock, flags); + port = gser->ioport; + + if (!port) { + spin_unlock_irqrestore(&serial_port_lock, flags); + return; + } + + spin_lock(&port->port_lock); + spin_unlock(&serial_port_lock); port->suspended = false; if (!port->start_delayed) { spin_unlock_irqrestore(&port->port_lock, flags);