[PATCH 3.12 115/142] USB: fix linked-list corruption in rh_call_control()

[Jiri Slaby]

From: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

commit 1633682053a7ee8058e10c76722b9b28e97fb73f upstream.

Using KASAN, Dmitry found a bug in the rh_call_control() routine: If
buffer allocation fails, the routine returns immediately without
unlinking its URB from the control endpoint, eventually leading to
linked-list corruption.

This patch fixes the problem by jumping to the end of the routine
(where the URB is unlinked) when an allocation failure occurs.

Signed-off-by: Alan Stern <stern@xxxxxxxxxxxxxxxxxxx>
Reported-and-tested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Jiri Slaby <jslaby@xxxxxxx>
---
 drivers/usb/core/hcd.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/usb/core/hcd.c b/drivers/usb/core/hcd.c
index 79055b3df45a..9925e4b6e2d3 100644
--- a/drivers/usb/core/hcd.c
+++ b/drivers/usb/core/hcd.c
@@ -498,8 +498,10 @@ static int rh_call_control (struct usb_hcd *hcd, struct urb *urb)
 	 */
 	tbuf_size =  max_t(u16, sizeof(struct usb_hub_descriptor), wLength);
 	tbuf = kzalloc(tbuf_size, GFP_KERNEL);
-	if (!tbuf)
-		return -ENOMEM;
+	if (!tbuf) {
+		status = -ENOMEM;
+		goto err_alloc;
+	}
 
 	bufp = tbuf;
 
@@ -702,6 +704,7 @@ error:
 	}
 
 	kfree(tbuf);
+ err_alloc:
 
 	/* any errors get returned through the urb completion */
 	spin_lock_irq(&hcd_root_hub_lock);
-- 
2.12.2