[Linux-kernel-mentees] [PATCH] usb: wusbcore: fix unbalanced get/put cluster_id

Phong Tran tranmanphong at gmail.com
Wed Jul 24 02:06:01 UTC 2019


syzboot reported that
https://syzkaller.appspot.com/bug?extid=fd2bd7df88c606eea4ef

There is not consitency parameter in cluste_id_get/put calling.
In case of getting the id with result is failure, the wusbhc->cluster_id
will not be updated and this can not be used for wusb_cluster_id_put().

Tested report
https://groups.google.com/d/msg/syzkaller-bugs/0znZopp3-9k/oxOrhLkLEgAJ

Reported-by: syzbot+fd2bd7df88c606eea4ef at syzkaller.appspotmail.com

Reproduce and gdb got the details:

139		addr = wusb_cluster_id_get();
(gdb) n
140		if (addr == 0)
(gdb) print addr
$1 = 254 '\376'
(gdb) n
142		result = __hwahc_set_cluster_id(hwahc, addr);
(gdb) print result
$2 = -71
(gdb) break wusb_cluster_id_put
Breakpoint 3 at 0xffffffff836e3f20: file drivers/usb/wusbcore/wusbhc.c, line 384.
(gdb) s
Thread 2 hit Breakpoint 3, wusb_cluster_id_put (id=0 '\000') at drivers/usb/wusbcore/wusbhc.c:384
384		id = 0xff - id;
(gdb) n
385		BUG_ON(id >= CLUSTER_IDS);
(gdb) print id
$3 = 255 '\377'

Signed-off-by: Phong Tran <tranmanphong at gmail.com>
---
 drivers/usb/host/hwa-hc.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/host/hwa-hc.c b/drivers/usb/host/hwa-hc.c
index 09a8ebd95588..6968b9f2b76b 100644
--- a/drivers/usb/host/hwa-hc.c
+++ b/drivers/usb/host/hwa-hc.c
@@ -159,7 +159,7 @@ static int hwahc_op_start(struct usb_hcd *usb_hcd)
 	return result;
 
 error_set_cluster_id:
-	wusb_cluster_id_put(wusbhc->cluster_id);
+	wusb_cluster_id_put(addr);
 error_cluster_id_get:
 	goto out;
 
-- 
2.20.1



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