If a task read/write data in blocking mode, it will wait the completion in ffs_epfile_io(), if function unbind occurs, ffs_func_unbind() will kfree ffs ep, once the task wake up, it still dereference the ffs ep to obtain the request status.

Fix it by moving the request status to io_data which is stack-safe.

Cc: stable@vger.kernel.org # 5.15 Reported-by: Michael Wu michael@allwinnertech.com Tested-by: Michael Wu michael@allwinnertech.com Reviewed-by: John Keeping john@metanate.com Signed-off-by: Linyu Yuan quic_linyyuan@quicinc.com --- v2: correct interrupted assignment v3: add Reviewed-by and Reported-by v4: add Tetsed-by from Michael Wu, remove one empty line cc stable kernel v5: change ?: to if/else format

drivers/usb/gadget/function/f_fs.c | 34 +++++++++++++++++++--------------- 1 file changed, 19 insertions(+), 15 deletions(-)

diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c index 4585ee3..e1fcd8b 100644 --- a/drivers/usb/gadget/function/f_fs.c +++ b/drivers/usb/gadget/function/f_fs.c @@ -122,8 +122,6 @@ struct ffs_ep { struct usb_endpoint_descriptor *descs[3];

u8 num; - - int status; /* P: epfile->mutex */ };

struct ffs_epfile { @@ -227,6 +225,9 @@ struct ffs_io_data { bool use_sg;

struct ffs_data *ffs; + + int status; + struct completion done; };

struct ffs_desc_helper { @@ -707,12 +708,15 @@ static const struct file_operations ffs_ep0_operations = {

static void ffs_epfile_io_complete(struct usb_ep *_ep, struct usb_request *req) { + struct ffs_io_data *io_data = req->context; + ENTER(); - if (req->context) { - struct ffs_ep *ep = _ep->driver_data; - ep->status = req->status ? req->status : req->actual; - complete(req->context); - } + if (req->status) + io_data->status = req->status; + else + io_data->status = req->actual; + + complete(&io_data->done); }

static ssize_t ffs_copy_to_iter(void *data, int data_len, struct iov_iter *iter) @@ -1050,7 +1054,6 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data) WARN(1, "%s: data_len == -EINVAL\n", __func__); ret = -EINVAL; } else if (!io_data->aio) { - DECLARE_COMPLETION_ONSTACK(done); bool interrupted = false;

req = ep->req; @@ -1066,7 +1069,8 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)

io_data->buf = data;

- req->context = &done; + init_completion(&io_data->done); + req->context = io_data; req->complete = ffs_epfile_io_complete;

ret = usb_ep_queue(ep->ep, req, GFP_ATOMIC); @@ -1075,7 +1079,7 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data)

spin_unlock_irq(&epfile->ffs->eps_lock);

- if (wait_for_completion_interruptible(&done)) { + if (wait_for_completion_interruptible(&io_data->done)) { /* * To avoid race condition with ffs_epfile_io_complete, * dequeue the request first then check @@ -1083,17 +1087,17 @@ static ssize_t ffs_epfile_io(struct file *file, struct ffs_io_data *io_data) * condition with req->complete callback. */ usb_ep_dequeue(ep->ep, req); - wait_for_completion(&done); - interrupted = ep->status < 0; + wait_for_completion(&io_data->done); + interrupted = io_data->status < 0; }

if (interrupted) ret = -EINTR; - else if (io_data->read && ep->status > 0) - ret = __ffs_epfile_read_data(epfile, data, ep->status, + else if (io_data->read && io_data->status > 0) + ret = __ffs_epfile_read_data(epfile, data, io_data->status, &io_data->data); else - ret = ep->status; + ret = io_data->status; goto error_mutex; } else if (!(req = usb_ep_alloc_request(ep->ep, GFP_ATOMIC))) { ret = -ENOMEM;