netdev - Double-lock bug in drivers/isdn/hardware/mISDN/hfcmulti.c

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Message-ID: <CAGbDTvrG+Wq6RUXogVXJRgb1QRLR2PYXv7xZ9_rQGwzVWCwcmQ@mail.gmail.com>
Date:   Fri, 4 May 2018 09:27:10 +0200
From:   Iago Abal <iago.abal@...il.com>
To:     Karsten Keil <isdn@...ux-pingi.de>,
        "David S. Miller" <davem@...emloft.net>,
        Stephen Hemminger <stephen@...workplumber.org>,
        Johannes Berg <johannes.berg@...el.com>,
        Arvind Yadav <arvind.yadav.cs@...il.com>,
        Kees Cook <keescook@...omium.org>, netdev@...r.kernel.org
Subject: Double-lock bug in drivers/isdn/hardware/mISDN/hfcmulti.c

Hi,

There is a potential double-lock sequence starting from hfc_remove_pci().

Forward trace:

  1. hfc_remove_pci()  LOCKS spin_lock_irqsave(&HFClock, flags) at 5284
  2. hfc_remove_pci()  calls release_card(card)                 at 5285
  3. release_card()    calls release_port(hc, hc->chan[ch].dch) at 4674
  4. release_port()    calls plxsd_checksync(hc, 1)             at 4595
  5. plxsd_checksync() calls hfcmulti_resync(hc, ..., rm)       at 1036 or 1044
  6. hfcmulti_resync() LOCKS spin_lock_irqsave(&HFClock, flags) at 933

NB: Bug found by static analysis thanks to EBA
(https://github.com/IagoAbal/eba).

Hope it helps,

-- iago