From: Young Xiao <92siuy...@gmail.com>
Date: Wed, 29 May 2019 16:48:59 +0800
> In drivers/isdn/hisax/isac.c, the function isac_interrupt() and
> ISAC_l1hw() may be concurrently executed.
>
> ISAC_l1hw()
> line 499: if (!cs->tx_skb)
>
> isac_interrupt()
> line 250: dev_kfree_skb_irq(cs->tx_skb);
>
> Thus, a possible concurrency use-after-free bug may occur in ISAC_l1hw().
...
> + spin_lock_irqsave(&cs->lock, flags);
> if (!cs->tx_skb) {
> test_and_clear_bit(FLG_L1_PULL_REQ, &st->l1.Flags);
> st->l1.l1l2(st, PH_PULL | CONFIRM, NULL);
> } else
> test_and_set_bit(FLG_L1_PULL_REQ, &st->l1.Flags);
> + spin_unlock_irqrestore(&cs->lock, flags);
Nothing in this code accesses the cs->tx_skb object. It is just a logic test
upon whether it is NULL or not.
I'm not applying stuff like this, sorry.
You have to show how something can actually go wrong when fixing a bug.
