From f01d35a15fa04162a58b95970fc01fa70ec9dacd Mon Sep 17 00:00:00 2001 From: Al Viro Date: Fri, 6 Feb 2015 02:07:45 -0500 Subject: [PATCH] gadgetfs: use-after-free in ->aio_read() AIO_PREAD requests call ->aio_read() with iovec on caller's stack, so if we are going to access it asynchronously, we'd better get ourselves a copy - the one on kernel stack of aio_run_iocb() won't be there anymore. function/f_fs.c take care of doing that, legacy/inode.c doesn't... Cc: stable@vger.kernel.org Signed-off-by: Al Viro --- drivers/usb/gadget/legacy/inode.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/usb/gadget/legacy/inode.c b/drivers/usb/gadget/legacy/inode.c index db49ec4c748e..9fbbaa041a31 100644 --- a/drivers/usb/gadget/legacy/inode.c +++ b/drivers/usb/gadget/legacy/inode.c @@ -566,7 +566,6 @@ static ssize_t ep_copy_to_user(struct kiocb_priv *priv) if (total == 0) break; } - return len; } @@ -585,6 +584,7 @@ static void ep_user_copy_worker(struct work_struct *work) aio_complete(iocb, ret, ret); kfree(priv->buf); + kfree(priv->iv); kfree(priv); } @@ -605,6 +605,7 @@ static void ep_aio_complete(struct usb_ep *ep, struct usb_request *req) */ if (priv->iv == NULL || unlikely(req->actual == 0)) { kfree(req->buf); + kfree(priv->iv); kfree(priv); iocb->private = NULL; /* aio_complete() reports bytes-transferred _and_ faults */ @@ -640,7 +641,7 @@ ep_aio_rwtail( struct usb_request *req; ssize_t value; - priv = kmalloc(sizeof *priv, GFP_KERNEL); + priv = kzalloc(sizeof *priv, GFP_KERNEL); if (!priv) { value = -ENOMEM; fail: @@ -649,7 +650,14 @@ fail: } iocb->private = priv; priv->iocb = iocb; - priv->iv = iv; + if (iv) { + priv->iv = kmemdup(iv, nr_segs * sizeof(struct iovec), + GFP_KERNEL); + if (!priv->iv) { + kfree(priv); + goto fail; + } + } priv->nr_segs = nr_segs; INIT_WORK(&priv->work, ep_user_copy_worker); @@ -689,6 +697,7 @@ fail: mutex_unlock(&epdata->lock); if (unlikely(value)) { + kfree(priv->iv); kfree(priv); put_ep(epdata); } else -- 2.11.0