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Message-Id: <20231005074858.65082-1-dg573847474@gmail.com>
Date: Thu, 5 Oct 2023 07:48:58 +0000
From: Chengfeng Ye <dg573847474@...il.com>
To: 3chas3@...il.com, davem@...emloft.net, horms@...nel.org
Cc: linux-atm-general@...ts.sourceforge.net, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, Chengfeng Ye <dg573847474@...il.com>
Subject: [PATCH v2 1/2] atm: solos-pci: Fix potential deadlock on &cli_queue_lock
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@...il.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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