From: Jiri Kosina <jkosina@suse.cz>
Date: Mon, 12 Oct 2009 09:25:56 +0000 (+0200)
Subject: HID: fix possible deadlock in hidraw_read
X-Git-Tag: v2.6.32-rc5~30^2
X-Git-Url: http://git.cascardo.info/?a=commitdiff_plain;ds=sidebyside;h=b0e14951ee0f6c29abc64b92ec7075a159ede37c;p=cascardo%2Flinux.git

HID: fix possible deadlock in hidraw_read

If the loop in hidraw_read() loops more than once, then we might
end up trying to acquire already locked mutex, casuing a deadlock.

Reported-by: iceberg <iceberg@ispras.ru>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
---

diff --git a/drivers/hid/hidraw.c b/drivers/hid/hidraw.c
index 0c6639ea03dd..b079a9c59958 100644
--- a/drivers/hid/hidraw.c
+++ b/drivers/hid/hidraw.c
@@ -47,10 +47,9 @@ static ssize_t hidraw_read(struct file *file, char __user *buffer, size_t count,
 	char *report;
 	DECLARE_WAITQUEUE(wait, current);
 
-	while (ret == 0) {
-
-		mutex_lock(&list->read_mutex);
+	mutex_lock(&list->read_mutex);
 
+	while (ret == 0) {
 		if (list->head == list->tail) {
 			add_wait_queue(&list->hidraw->wait, &wait);
 			set_current_state(TASK_INTERRUPTIBLE);