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 c6f6560..0bb2b32 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -157,8 +157,9 @@
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 @@
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 @@
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 {