Messages in this thread Patch in this message | | | From | 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 |
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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.
<deadlock #1> console_show() --> spin_lock(&card->cli_queue_lock) <interrupt> --> 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 <dg573847474@gmail.com> --- 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
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