From: NeilBrown <neilb@suse.de> stable inclusion from stable-v5.10.110 commit b7b430104a14a05c74297e794a0fe237f822ebb1 bugzilla: https://gitee.com/openeuler/kernel/issues/I574AL Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 3848e96edf4788f772d83990022fa7023a233d83 upstream. xprt_destory() claims XPRT_LOCKED and then calls del_timer_sync(). Both xprt_unlock_connect() and xprt_release() call ->release_xprt() which drops XPRT_LOCKED and *then* xprt_schedule_autodisconnect() which calls mod_timer(). This may result in mod_timer() being called *after* del_timer_sync(). When this happens, the timer may fire long after the xprt has been freed, and run_timer_softirq() will probably crash. The pairing of ->release_xprt() and xprt_schedule_autodisconnect() is always called under ->transport_lock. So if we take ->transport_lock to call del_timer_sync(), we can be sure that mod_timer() will run first (if it runs at all). Cc: stable@vger.kernel.org Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Yu Liao <liaoyu15@huawei.com> Reviewed-by: Wei Li <liwei391@huawei.com> Signed-off-by: Zheng Zengkai <zhengzengkai@huawei.com> --- net/sunrpc/xprt.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/net/sunrpc/xprt.c b/net/sunrpc/xprt.c index 5c8c5b38faf1..3ea27bb3f512 100644 --- a/net/sunrpc/xprt.c +++ b/net/sunrpc/xprt.c @@ -2054,7 +2054,14 @@ static void xprt_destroy(struct rpc_xprt *xprt) */ wait_on_bit_lock(&xprt->state, XPRT_LOCKED, TASK_UNINTERRUPTIBLE); + /* + * xprt_schedule_autodisconnect() can run after XPRT_LOCKED + * is cleared. We use ->transport_lock to ensure the mod_timer() + * can only run *before* del_time_sync(), never after. + */ + spin_lock(&xprt->transport_lock); del_timer_sync(&xprt->timer); + spin_unlock(&xprt->transport_lock); /* * Destroy sockets etc from the system workqueue so they can -- 2.20.1