From 197d1155b07b582d9969f456f61ee07d632af7e1 Mon Sep 17 00:00:00 2001 From: Oliver Neukum Date: Thu, 26 Apr 2012 21:59:10 +0200 Subject: [PATCH] USB: cdc-wdm: fix race leading leading to memory corruption MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit commit 5c22837adca7c30b66121cf18ad3e160134268d4 upstream. 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 Tested-by: Bjørn Mork Signed-off-by: Greg Kroah-Hartman --- drivers/usb/class/cdc-wdm.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c index 76f061375e14..00b7bf9a20ce 100644 --- a/drivers/usb/class/cdc-wdm.c +++ b/drivers/usb/class/cdc-wdm.c @@ -108,8 +108,9 @@ 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); } @@ -312,7 +313,7 @@ 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; @@ -376,10 +377,12 @@ 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 { -- 2.39.5