From: Oliver Neukum <oliver@neukum.org>
Date: Thu, 26 Apr 2012 19:59:10 +0000 (+0200)
Subject: USB: cdc-wdm: fix race leading leading to memory corruption
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=5c22837adca7c30b66121cf18ad3e160134268d4;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git

USB: cdc-wdm: fix race leading leading to memory corruption

This patch fixes a race whereby a pointer to a buffer
would be overwritten while the buffer was in use leading
to a double free and a memory leak. This causes crashes.
This bug was introduced in 2.6.34

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Tested-by: Bjørn Mork <bjorn@mork.no>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index c6f6560d436c..0bb2b3248dad 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -157,8 +157,9 @@ static void wdm_out_callback(struct urb *urb)
 	spin_lock(&desc->iuspin);
 	desc->werr = urb->status;
 	spin_unlock(&desc->iuspin);
-	clear_bit(WDM_IN_USE, &desc->flags);
 	kfree(desc->outbuf);
+	desc->outbuf = NULL;
+	clear_bit(WDM_IN_USE, &desc->flags);
 	wake_up(&desc->wait);
 }
 
@@ -338,7 +339,7 @@ static ssize_t wdm_write
 	if (we < 0)
 		return -EIO;
 
-	desc->outbuf = buf = kmalloc(count, GFP_KERNEL);
+	buf = kmalloc(count, GFP_KERNEL);
 	if (!buf) {
 		rv = -ENOMEM;
 		goto outnl;
@@ -406,10 +407,12 @@ static ssize_t wdm_write
 	req->wIndex = desc->inum;
 	req->wLength = cpu_to_le16(count);
 	set_bit(WDM_IN_USE, &desc->flags);
+	desc->outbuf = buf;
 
 	rv = usb_submit_urb(desc->command, GFP_KERNEL);
 	if (rv < 0) {
 		kfree(buf);
+		desc->outbuf = NULL;
 		clear_bit(WDM_IN_USE, &desc->flags);
 		dev_err(&desc->intf->dev, "Tx URB error: %d\n", rv);
 	} else {