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[143.89.191.97]) by smtp.gmail.com with ESMTPSA id a23-20020a637057000000b0054ff36967f7sm921961pgn.54.2023.07.27.01.56.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 27 Jul 2023 01:56:33 -0700 (PDT) From: Chengfeng Ye To: isdn@linux-pingi.de, alexanderduyck@fb.com, duoming@zju.edu.cn, yangyingliang@huawei.com, davem@davemloft.net, kuba@kernel.org Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Chengfeng Ye Subject: [PATCH v2] mISDN: hfcpci: Fix potential deadlock on &hc->lock Date: Thu, 27 Jul 2023 08:56:19 +0000 Message-Id: <20230727085619.7419-1-dg573847474@gmail.com> X-Mailer: git-send-email 2.17.1 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" As &hc->lock is acquired by both timer _hfcpci_softirq() and hardirq hfcpci_int(), the timer should disable irq before lock acquisition otherwise deadlock could happen if the timmer is preemtped by the hadr irq. Possible deadlock scenario: hfcpci_softirq() (timer) -> _hfcpci_softirq() -> spin_lock(&hc->lock); -> hfcpci_int() -> spin_lock(&hc->lock); (deadlock here) This flaw was found by an experimental static analysis tool I am developing for irq-related deadlock. The tentative patch fixes the potential deadlock by spin_lock_irq() in timer. Fixes: b36b654a7e82 ("mISDN: Create /sys/class/mISDN") Signed-off-by: Chengfeng Ye Changes in v2 - change dev_kfree_skb() to dev_kfree_skb_any() inside spin_lock_irq() critical region --- drivers/isdn/hardware/mISDN/hfcpci.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/isdn/hardware/mISDN/hfcpci.c b/drivers/isdn/hardware/m= ISDN/hfcpci.c index c0331b268010..fe391de1aba3 100644 --- a/drivers/isdn/hardware/mISDN/hfcpci.c +++ b/drivers/isdn/hardware/mISDN/hfcpci.c @@ -839,7 +839,7 @@ hfcpci_fill_fifo(struct bchannel *bch) *z1t =3D cpu_to_le16(new_z1); /* now send data */ if (bch->tx_idx < bch->tx_skb->len) return; - dev_kfree_skb(bch->tx_skb); + dev_kfree_skb_any(bch->tx_skb); if (get_next_bframe(bch)) goto next_t_frame; return; @@ -895,7 +895,7 @@ hfcpci_fill_fifo(struct bchannel *bch) } bz->za[new_f1].z1 =3D cpu_to_le16(new_z1); /* for next buffer */ bz->f1 =3D new_f1; /* next frame */ - dev_kfree_skb(bch->tx_skb); + dev_kfree_skb_any(bch->tx_skb); get_next_bframe(bch); } =20 @@ -1119,7 +1119,7 @@ tx_birq(struct bchannel *bch) if (bch->tx_skb && bch->tx_idx < bch->tx_skb->len) hfcpci_fill_fifo(bch); else { - dev_kfree_skb(bch->tx_skb); + dev_kfree_skb_any(bch->tx_skb); if (get_next_bframe(bch)) hfcpci_fill_fifo(bch); } @@ -2277,7 +2277,7 @@ _hfcpci_softirq(struct device *dev, void *unused) return 0; =20 if (hc->hw.int_m2 & HFCPCI_IRQ_ENABLE) { - spin_lock(&hc->lock); + spin_lock_irq(&hc->lock); bch =3D Sel_BCS(hc, hc->hw.bswapped ? 2 : 1); if (bch && bch->state =3D=3D ISDN_P_B_RAW) { /* B1 rx&tx */ main_rec_hfcpci(bch); @@ -2288,7 +2288,7 @@ _hfcpci_softirq(struct device *dev, void *unused) main_rec_hfcpci(bch); tx_birq(bch); } - spin_unlock(&hc->lock); + spin_unlock_irq(&hc->lock); } return 0; } --=20 2.17.1