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[143.89.191.97]) by smtp.gmail.com with ESMTPSA id y14-20020a17090a134e00b00277560ecd5dsm2772178pjf.46.2023.10.05.00.49.08 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 05 Oct 2023 00:49:10 -0700 (PDT) From: Chengfeng Ye To: 3chas3@gmail.com, davem@davemloft.net, horms@kernel.org Cc: linux-atm-general@lists.sourceforge.net, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, Chengfeng Ye Subject: [PATCH v2 1/2] atm: solos-pci: Fix potential deadlock on &cli_queue_lock Date: Thu, 5 Oct 2023 07:48:58 +0000 Message-Id: <20231005074858.65082-1-dg573847474@gmail.com> X-Mailer: git-send-email 2.17.1 X-Spam-Status: No, score=-1.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_ENVFROM_END_DIGIT, FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: As &card->cli_queue_lock is acquired under softirq context along the following call chain from solos_bh(), other acquisition of the same lock inside process context should disable at least bh to avoid double lock. console_show() --> spin_lock(&card->cli_queue_lock) --> solos_bh() --> spin_lock(&card->cli_queue_lock) This flaw was found by an experimental static analysis tool I am developing for irq-related deadlock. To prevent the potential deadlock, the patch uses spin_lock_irqsave() on the card->cli_queue_lock under process context code consistently to prevent the possible deadlock scenario. Fixes: 9c54004ea717 ("atm: Driver for Solos PCI ADSL2+ card.") Signed-off-by: Chengfeng Ye --- V2: add fix tag, and slipt into two patches drivers/atm/solos-pci.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/atm/solos-pci.c b/drivers/atm/solos-pci.c index 94fbc3abe60e..48cf9b36b61a 100644 --- a/drivers/atm/solos-pci.c +++ b/drivers/atm/solos-pci.c @@ -447,11 +447,12 @@ static ssize_t console_show(struct device *dev, struct device_attribute *attr, struct atm_dev *atmdev = container_of(dev, struct atm_dev, class_dev); struct solos_card *card = atmdev->dev_data; struct sk_buff *skb; + unsigned long flags; unsigned int len; - spin_lock(&card->cli_queue_lock); + spin_lock_irqsave(&card->cli_queue_lock, flags); skb = skb_dequeue(&card->cli_queue[SOLOS_CHAN(atmdev)]); - spin_unlock(&card->cli_queue_lock); + spin_unlock_irqrestore(&card->cli_queue_lock, flags); if(skb == NULL) return sprintf(buf, "No data.\n"); -- 2.17.1