7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Mika Westerberg commit a02188ddc24b7872f0c5e0c5873f827318717803 upstream. Alan reported that when doing stress testing sometimes KASAN notices use-after-free during control channel operation (stripped down keeping the relevant parts): BUG: KASAN: slab-use-after-free in tb_cfg_request_sync+0x240/0x250 [thunderbolt] Read of size 24 at addr ffff88811067f290 by task kworker/u40:2/1760 tb_cfg_request_sync+0x240/0x250 [thunderbolt] tb_cfg_read_raw+0x367/0x510 [thunderbolt] tb_cfg_read+0xec/0x240 [thunderbolt] tb_port_get_link_generation+0x258/0x420 [thunderbolt] tb_usb3_consumed_bandwidth+0x1c1/0x2c0 [thunderbolt] tb_tunnel_consumed_bandwidth+0xfd/0x910 [thunderbolt] tb_available_bandwidth+0x5f2/0xeb0 [thunderbolt] tb_recalc_estimated_bandwidth+0x2a0/0x1bc0 [thunderbolt] tb_handle_dp_bandwidth_request+0x1897/0x5e20 [thunderbolt] process_one_work+0x675/0x1230 worker_thread+0x5e6/0xf70 kthread+0x365/0x470 ret_from_fork+0x54d/0x710 ret_from_fork_asm+0x1a/0x30 Allocated by task 1760: __kmalloc_cache_noprof+0x1ee/0x550 tb_cfg_read_raw+0x1d3/0x510 [thunderbolt] tb_cfg_read+0xec/0x240 [thunderbolt] tb_port_get_link_generation+0x258/0x420 [thunderbolt] tb_usb3_consumed_bandwidth+0x1c1/0x2c0 [thunderbolt] tb_tunnel_consumed_bandwidth+0xfd/0x910 [thunderbolt] tb_available_bandwidth+0x5f2/0xeb0 [thunderbolt] tb_recalc_estimated_bandwidth+0x2a0/0x1bc0 [thunderbolt] tb_handle_dp_bandwidth_request+0x1897/0x5e20 [thunderbolt] process_one_work+0x675/0x1230 worker_thread+0x5e6/0xf70 kthread+0x365/0x470 ret_from_fork+0x54d/0x710 ret_from_fork_asm+0x1a/0x30 Freed by task 926: kfree+0x18f/0x4a0 tb_cfg_request_put+0xb7/0xe0 [thunderbolt] tb_cfg_request_work+0x82/0x120 [thunderbolt] process_one_work+0x675/0x1230 worker_thread+0x5e6/0xf70 kthread+0x365/0x470 ret_from_fork+0x54d/0x710 ret_from_fork_asm+0x1a/0x30 Second to last potentially related work creation: __queue_work+0x575/0xd00 queue_work_on+0x77/0x80 tb_cfg_request_cancel+0xc7/0x260 [thunderbolt] tb_cfg_request_sync+0x1f6/0x250 [thunderbolt] tb_cfg_read_raw+0x367/0x510 [thunderbolt] tb_cfg_read+0xec/0x240 [thunderbolt] tb_port_get_link_generation+0x258/0x420 [thunderbolt] tb_usb3_consumed_bandwidth+0x1c1/0x2c0 [thunderbolt] tb_tunnel_consumed_bandwidth+0xfd/0x910 [thunderbolt] tb_available_bandwidth+0x5f2/0xeb0 [thunderbolt] tb_recalc_estimated_bandwidth+0x2a0/0x1bc0 [thunderbolt] tb_handle_dp_bandwidth_request+0x1897/0x5e20 [thunderbolt] process_one_work+0x675/0x1230 worker_thread+0x5e6/0xf70 kthread+0x365/0x470 ret_from_fork+0x54d/0x710 ret_from_fork_asm+0x1a/0x30 The last stack trace is helpful because it shows that we are cancelling a request and looking at tb_cfg_request_cancel() what might happen is that tb_cfg_request_work() completes right before tb_cfg_request_cancel() starts and because of this it will call schedule_work() queueing the same work to run again. However, it is already removed from the request_queue and reference count is dropped so when tb_cfg_request_work() triggers again it will access memory that is already released. Fix this so that we first make sure a cancelled request is not handed away from tb_cfg_request_find() or scheduled to run. Then instead of relying on the worker to clean up the request we will do it in tb_cfg_request_cancel() after the work is canceled from running. Make tb_cfg_request_dequeue() release the request only if it was actually removed from the queue. Reported-by: Alan Borzeszkowski Fixes: d7f781bfdbf4 ("thunderbolt: Rework control channel to be more reliable") Cc: stable@vger.kernel.org Signed-off-by: Mika Westerberg Signed-off-by: Greg Kroah-Hartman --- drivers/thunderbolt/ctl.c | 63 ++++++++++++++++++++++------------------------ 1 file changed, 31 insertions(+), 32 deletions(-) --- a/drivers/thunderbolt/ctl.c +++ b/drivers/thunderbolt/ctl.c @@ -73,7 +73,6 @@ struct tb_ctl { #define tb_ctl_dbg_once(ctl, format, arg...) \ dev_dbg_once((ctl)->nhi->dev, format, ## arg) -static DECLARE_WAIT_QUEUE_HEAD(tb_cfg_request_cancel_queue); /* Serializes access to request kref_get/put */ static DEFINE_MUTEX(tb_cfg_request_lock); @@ -133,41 +132,42 @@ void tb_cfg_request_put(struct tb_cfg_re static int tb_cfg_request_enqueue(struct tb_ctl *ctl, struct tb_cfg_request *req) { + tb_cfg_request_get(req); + WARN_ON(test_bit(TB_CFG_REQUEST_ACTIVE, &req->flags)); WARN_ON(req->ctl); - mutex_lock(&ctl->request_queue_lock); + guard(mutex)(&ctl->request_queue_lock); if (!ctl->running) { - mutex_unlock(&ctl->request_queue_lock); + tb_cfg_request_put(req); return -ENOTCONN; } req->ctl = ctl; list_add_tail(&req->list, &ctl->request_queue); set_bit(TB_CFG_REQUEST_ACTIVE, &req->flags); - mutex_unlock(&ctl->request_queue_lock); return 0; } -static void tb_cfg_request_dequeue(struct tb_cfg_request *req) +static bool tb_cfg_request_is_active(struct tb_cfg_request *req) { - struct tb_ctl *ctl = req->ctl; - - mutex_lock(&ctl->request_queue_lock); - if (!test_bit(TB_CFG_REQUEST_ACTIVE, &req->flags)) { - mutex_unlock(&ctl->request_queue_lock); - return; - } + return test_bit(TB_CFG_REQUEST_ACTIVE, &req->flags); +} - list_del(&req->list); - clear_bit(TB_CFG_REQUEST_ACTIVE, &req->flags); - if (test_bit(TB_CFG_REQUEST_CANCELED, &req->flags)) - wake_up(&tb_cfg_request_cancel_queue); - mutex_unlock(&ctl->request_queue_lock); +static bool tb_cfg_request_is_canceled(struct tb_cfg_request *req) +{ + return test_bit(TB_CFG_REQUEST_CANCELED, &req->flags); } -static bool tb_cfg_request_is_active(struct tb_cfg_request *req) +static void tb_cfg_request_dequeue(struct tb_cfg_request *req) { - return test_bit(TB_CFG_REQUEST_ACTIVE, &req->flags); + struct tb_ctl *ctl = req->ctl; + + guard(mutex)(&ctl->request_queue_lock); + if (tb_cfg_request_is_active(req)) { + list_del(&req->list); + clear_bit(TB_CFG_REQUEST_ACTIVE, &req->flags); + tb_cfg_request_put(req); + } } static struct tb_cfg_request * @@ -178,7 +178,7 @@ tb_cfg_request_find(struct tb_ctl *ctl, mutex_lock(&pkg->ctl->request_queue_lock); list_for_each_entry(iter, &pkg->ctl->request_queue, list) { tb_cfg_request_get(iter); - if (iter->match(iter, pkg)) { + if (!tb_cfg_request_is_canceled(iter) && iter->match(iter, pkg)) { req = iter; break; } @@ -512,8 +512,11 @@ static void tb_ctl_rx_callback(struct tb trace_tb_rx(pkg->ctl->index, frame->eof, pkg->buffer, frame->size, !req); if (req) { - if (req->copy(req, pkg)) - schedule_work(&req->work); + scoped_guard(mutex, &pkg->ctl->request_queue_lock) { + if (!tb_cfg_request_is_canceled(req) && + req->copy(req, pkg)) + schedule_work(&req->work); + } tb_cfg_request_put(req); } @@ -525,11 +528,10 @@ static void tb_cfg_request_work(struct w { struct tb_cfg_request *req = container_of(work, typeof(*req), work); - if (!test_bit(TB_CFG_REQUEST_CANCELED, &req->flags)) + if (!tb_cfg_request_is_canceled(req)) req->callback(req->callback_data); tb_cfg_request_dequeue(req); - tb_cfg_request_put(req); } /** @@ -555,10 +557,9 @@ int tb_cfg_request(struct tb_ctl *ctl, s INIT_WORK(&req->work, tb_cfg_request_work); INIT_LIST_HEAD(&req->list); - tb_cfg_request_get(req); ret = tb_cfg_request_enqueue(ctl, req); if (ret) - goto err_put; + return ret; ret = tb_ctl_tx(ctl, req->request, req->request_size, req->request_type); @@ -572,9 +573,6 @@ int tb_cfg_request(struct tb_ctl *ctl, s err_dequeue: tb_cfg_request_dequeue(req); -err_put: - tb_cfg_request_put(req); - return ret; } @@ -588,9 +586,10 @@ err_put: */ void tb_cfg_request_cancel(struct tb_cfg_request *req, int err) { - set_bit(TB_CFG_REQUEST_CANCELED, &req->flags); - schedule_work(&req->work); - wait_event(tb_cfg_request_cancel_queue, !tb_cfg_request_is_active(req)); + scoped_guard(mutex, &req->ctl->request_queue_lock) + set_bit(TB_CFG_REQUEST_CANCELED, &req->flags); + cancel_work_sync(&req->work); + tb_cfg_request_dequeue(req); req->result.err = err; }