From: Eric Van Hensbergen <ericvh@kernel.org>
To: v9fs@lists.linux.dev
Subject: [zyytlz.wz@163.com: [V9fs-developer] [PATCH net v3] 9p/xen : Fix use after free bug in xen_9pfs_front_remove due to race condition]
Date: Sun, 2 Apr 2023 00:42:28 +0000 [thread overview]
Message-ID: <ZCjPdIkEQ0ALhdUU@7e9e31583646> (raw)
----- Forwarded message from Zheng Wang <zyytlz.wz@163.com> -----
Date: Mon, 13 Mar 2023 22:43:25 +0800
From: Zheng Wang <zyytlz.wz@163.com>
To: ericvh@gmail.com
Cc: lucho@ionkov.net, alex000young@gmail.com, Zheng Wang <zyytlz.wz@163.com>, 1395428693sheep@gmail.com, netdev@vger.kernel.org, linux_oss@crudebyte.com, linux-kernel@vger.kernel.org, hackerzheng666@gmail.com, v9fs-developer@lists.sourceforge.net, edumazet@google.com, kuba@kernel.org,
michal.swiatkowski@linux.intel.com, pabeni@redhat.com, davem@davemloft.net
Subject: [V9fs-developer] [PATCH net v3] 9p/xen : Fix use after free bug in xen_9pfs_front_remove due to race condition
X-Mailer: git-send-email 2.25.1
In xen_9pfs_front_probe, it calls xen_9pfs_front_alloc_dataring
to init priv->rings and bound &ring->work with p9_xen_response.
When it calls xen_9pfs_front_event_handler to handle IRQ requests,
it will finally call schedule_work to start the work.
When we call xen_9pfs_front_remove to remove the driver, there
may be a sequence as follows:
Fix it by finishing the work before cleanup in xen_9pfs_front_free.
Note that, this bug is found by static analysis, which might be
false positive.
CPU0 CPU1
|p9_xen_response
xen_9pfs_front_remove|
xen_9pfs_front_free|
kfree(priv) |
//free priv |
|p9_tag_lookup
|//use priv->client
Fixes: 71ebd71921e4 ("xen/9pfs: connect to the backend")
Signed-off-by: Zheng Wang <zyytlz.wz@163.com>
---
v3:
- remove unnecessary comment and move definition to the
for loop suggested by Michal Swiatkowski
v2:
- fix type error of ring found by kernel test robot
---
net/9p/trans_xen.c | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c
index c64050e839ac..df467ffb52d0 100644
--- a/net/9p/trans_xen.c
+++ b/net/9p/trans_xen.c
@@ -280,6 +280,10 @@ static void xen_9pfs_front_free(struct xen_9pfs_front_priv *priv)
write_unlock(&xen_9pfs_lock);
for (i = 0; i < priv->num_rings; i++) {
+ struct xen_9pfs_dataring *ring = &priv->rings[i];
+
+ cancel_work_sync(&ring->work);
+
if (!priv->rings[i].intf)
break;
if (priv->rings[i].irq > 0)
--
2.25.1
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----- End forwarded message -----
reply other threads:[~2023-04-02 0:42 UTC|newest]
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