From 2a14759a03a0a57b2fc99b1e416180788b8ba24c Mon Sep 17 00:00:00 2001
From: Oliver Neukum <oneukum@suse.com>
Date: Mon, 4 Apr 2016 14:30:53 +0200
Subject: cdc-acm: fix crash if flushed with nothing buffered
Under some circumstances acm_tty_flush_chars() is called
with no buffer to flush. We simply need to do nothing.
Signed-off-by: Oliver Neukum <ONeukum@suse.com>
Reported-by: Torsten Hilbrich <torsten.hilbrich@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/class/cdc-acm.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 83fd30b0577c..a6c4a1b895bd 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -744,11 +744,15 @@ static void acm_tty_flush_chars(struct tty_struct *tty)
int err;
unsigned long flags;
+ if (!cur) /* nothing to do */
+ return;
+
acm->putbuffer = NULL;
err = usb_autopm_get_interface_async(acm->control);
spin_lock_irqsave(&acm->write_lock, flags);
if (err < 0) {
cur->use = 0;
+ acm->putbuffer = cur;
goto out;
}
--
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