From c08c464d6f4136d9e48ffa23c0bcd93442343b2a Mon Sep 17 00:00:00 2001
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Mon, 15 Apr 2013 16:31:13 -0400
Subject: [PATCH] mISDN: fix the races with timers going off just as they are
deleted
timer callback in timerdev.c both accesses struct mISDNtimer it's
called for *and* moves it to dev->expired. We need del_timer_sync(),
or we risk kfree() freeing it right under dev_expire_timer() *and*
dev->expired getting corrupted.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
---
drivers/isdn/mISDN/timerdev.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)
diff --git a/drivers/isdn/mISDN/timerdev.c b/drivers/isdn/mISDN/timerdev.c
index 1094667d8f31..5a1a5cadc766 100644
--- a/drivers/isdn/mISDN/timerdev.c
+++ b/drivers/isdn/mISDN/timerdev.c
@@ -72,14 +72,24 @@ static int
mISDN_close(struct inode *ino, struct file *filep)
{
struct mISDNtimerdev *dev = filep->private_data;
+ struct list_head *list = &dev->pending;
struct mISDNtimer *timer, *next;
if (*debug & DEBUG_TIMER)
printk(KERN_DEBUG "%s(%p,%p)\n", __func__, ino, filep);
- list_for_each_entry_safe(timer, next, &dev->pending, list) {
- del_timer(&timer->tl);
+
+ spin_lock_irq(&dev->lock);
+ while (!list_empty(list)) {
+ timer = list_first_entry(list, struct mISDNtimer, list);
+ spin_unlock_irq(&dev->lock);
+ del_timer_sync(&timer->tl);
+ spin_lock_irq(&dev->lock);
+ /* it might have been moved to ->expired */
+ list_del(&timer->list);
kfree(timer);
}
+ spin_unlock_irq(&dev->lock);
+
list_for_each_entry_safe(timer, next, &dev->expired, list) {
kfree(timer);
}
--
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