From: Chengfeng Ye <dg573847474@gmail.com>
To: jreuter@yaina.de, ralf@linux-mips.org, davem@davemloft.net,
edumazet@google.com, kuba@kernel.org, pabeni@redhat.com,
horms@kernel.org
Cc: linux-hams@vger.kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org,
Chengfeng Ye <dg573847474@gmail.com>
Subject: [PATCH V2] ax25: Fix potential deadlock on &ax25_list_lock
Date: Thu, 5 Oct 2023 07:23:49 +0000 [thread overview]
Message-ID: <20231005072349.52602-1-dg573847474@gmail.com> (raw)
Timer interrupt ax25_ds_timeout() could introduce double locks on
&ax25_list_lock.
ax25_ioctl()
--> ax25_ctl_ioctl()
--> ax25_dama_off()
--> ax25_dev_dama_off()
--> ax25_check_dama_slave()
--> spin_lock(&ax25_list_lock)
<timer interrupt>
--> ax25_ds_timeout()
--> spin_lock(&ax25_list_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 use spin_lock_bh()
on &ax25_list_lock inside ax25_check_dama_slave().
Fixes: c19c4b9c9acb ("[AX.25]: Optimize AX.25 socket list lock")
Signed-off-by: Chengfeng Ye <dg573847474@gmail.com>
---
V2: add fixes tag
net/ax25/ax25_ds_subr.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/net/ax25/ax25_ds_subr.c b/net/ax25/ax25_ds_subr.c
index f00e27df3c76..010b11303d32 100644
--- a/net/ax25/ax25_ds_subr.c
+++ b/net/ax25/ax25_ds_subr.c
@@ -156,13 +156,13 @@ static int ax25_check_dama_slave(ax25_dev *ax25_dev)
ax25_cb *ax25;
int res = 0;
- spin_lock(&ax25_list_lock);
+ spin_lock_bh(&ax25_list_lock);
ax25_for_each(ax25, &ax25_list)
if (ax25->ax25_dev == ax25_dev && (ax25->condition & AX25_COND_DAMA_MODE) && ax25->state > AX25_STATE_1) {
res = 1;
break;
}
- spin_unlock(&ax25_list_lock);
+ spin_unlock_bh(&ax25_list_lock);
return res;
}
--
2.17.1
next reply other threads:[~2023-10-05 14:12 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-05 7:23 Chengfeng Ye [this message]
2023-10-07 15:10 ` [PATCH V2] ax25: Fix potential deadlock on &ax25_list_lock Simon Horman
2023-10-07 15:43 ` Chengfeng Ye
2023-10-09 14:55 ` Simon Horman
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