From: Sun Ke <sunke32@huawei.com>
To: <josef@toxicpanda.com>, <axboe@kernel.dk>, <mchristi@redhat.com>,
<sunke32@huawei.com>
Cc: <linux-block@vger.kernel.org>, <nbd@other.debian.org>,
<linux-kernel@vger.kernel.org>
Subject: [v3] nbd: fix potential NULL pointer fault in nbd_genl_disconnect
Date: Mon, 10 Feb 2020 15:32:41 +0800 [thread overview]
Message-ID: <20200210073241.41813-1-sunke32@huawei.com> (raw)
Open /dev/nbdX first, the config_refs will be 1 and
the pointers in nbd_device are still null. Disconnect
/dev/nbdX, then reference a null recv_workq. The
protection by config_refs in nbd_genl_disconnect is useless.
To fix it, just add a check for a non null task_recv in
nbd_genl_disconnect.
Signed-off-by: Sun Ke <sunke32@huawei.com>
---
v1 -> v2:
Add an omitted mutex_unlock.
v2 -> v3:
Add nbd->config_lock, suggested by Josef.
---
drivers/block/nbd.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index b4607dd96185..870b3fd0c101 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -2008,12 +2008,20 @@ static int nbd_genl_disconnect(struct sk_buff *skb, struct genl_info *info)
index);
return -EINVAL;
}
+ mutex_lock(&nbd->config_lock);
if (!refcount_inc_not_zero(&nbd->refs)) {
+ mutex_unlock(&nbd->config_lock);
mutex_unlock(&nbd_index_mutex);
printk(KERN_ERR "nbd: device at index %d is going down\n",
index);
return -EINVAL;
}
+ if (!nbd->recv_workq) {
+ mutex_unlock(&nbd->config_lock);
+ mutex_unlock(&nbd_index_mutex);
+ return -EINVAL;
+ }
+ mutex_unlock(&nbd->config_lock);
mutex_unlock(&nbd_index_mutex);
if (!refcount_inc_not_zero(&nbd->config_refs)) {
nbd_put(nbd);
--
2.17.2
next reply other threads:[~2020-02-10 7:33 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-02-10 7:32 Sun Ke [this message]
2020-02-10 17:05 ` [v3] nbd: fix potential NULL pointer fault in nbd_genl_disconnect Mike Christie
2020-02-11 4:12 ` sunke (E)
2020-02-11 16:39 ` Mike Christie
2020-02-12 2:00 ` sunke (E)
2020-06-01 11:41 ` Sun Ke
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