From: Zheng Wang Date: Mon, 13 Mar 2023 14:43:25 +0000 (+0800) Subject: 9p/xen : Fix use after free bug in xen_9pfs_front_remove due to race condition X-Git-Tag: v6.1.37~2235 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c4002b9d5e837f152a40d1333c56ccb84975147b;p=platform%2Fkernel%2Flinux-starfive.git 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 Reviewed-by: Michal Swiatkowski Signed-off-by: Eric Van Hensbergen Signed-off-by: Sasha Levin --- diff --git a/net/9p/trans_xen.c b/net/9p/trans_xen.c index 75c03a8..68027e4f 100644 --- a/net/9p/trans_xen.c +++ b/net/9p/trans_xen.c @@ -278,6 +278,10 @@ 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)