]> www.infradead.org Git - users/jedix/linux-maple.git/commit
9p/xen : Fix use after free bug in xen_9pfs_front_remove due to race condition
authorZheng Wang <zyytlz.wz@163.com>
Mon, 13 Mar 2023 14:43:25 +0000 (22:43 +0800)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 20 Apr 2023 10:35:08 +0000 (12:35 +0200)
commitc4002b9d5e837f152a40d1333c56ccb84975147b
treebbe50ec68e4a511dab1625b530d7c00ecda547c1
parentb7abd535881a48587961c2099b1d2933ebd42c4b
9p/xen : Fix use after free bug in xen_9pfs_front_remove due to race condition

[ Upstream commit ea4f1009408efb4989a0f139b70fb338e7f687d0 ]

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>
Reviewed-by: Michal Swiatkowski <michal.swiatkowski@linux.intel.com>
Signed-off-by: Eric Van Hensbergen <ericvh@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net/9p/trans_xen.c