From e7b931bee739e8a77ae216e613d3b99342b6dec0 Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Wed, 15 Jul 2020 11:02:45 +0200
Subject: [PATCH] USB: serial: iuu_phoenix: fix memory corruption
Git-commit: e7b931bee739e8a77ae216e613d3b99342b6dec0
Patch-mainline: v5.8-rc6
References: bsc#1111666
The driver would happily overwrite its write buffer with user data in
256 byte increments due to a removed buffer-space sanity check.
Fixes: 5fcf62b0f1f2 ("tty: iuu_phoenix: fix locking.")
Cc: stable <stable@vger.kernel.org> # 2.6.31
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/usb/serial/iuu_phoenix.c | 8 +++++---
1 file changed, 5 insertions(+), 3 deletions(-)
diff --git a/drivers/usb/serial/iuu_phoenix.c b/drivers/usb/serial/iuu_phoenix.c
index d5bff69b1769..b8dfeb4fb2ed 100644
--- a/drivers/usb/serial/iuu_phoenix.c
+++ b/drivers/usb/serial/iuu_phoenix.c
@@ -697,14 +697,16 @@ static int iuu_uart_write(struct tty_struct *tty, struct usb_serial_port *port,
struct iuu_private *priv = usb_get_serial_port_data(port);
unsigned long flags;
- if (count > 256)
- return -ENOMEM;
-
spin_lock_irqsave(&priv->lock, flags);
+ count = min(count, 256 - priv->writelen);
+ if (count == 0)
+ goto out;
+
/* fill the buffer */
memcpy(priv->writebuf + priv->writelen, buf, count);
priv->writelen += count;
+out:
spin_unlock_irqrestore(&priv->lock, flags);
return count;
--
2.16.4