From mboxrd@z Thu Jan 1 00:00:00 1970 From: Al Viro Subject: [PATCH 5/6] gadgetfs: use-after-free in ->aio_read() Date: Sat, 7 Feb 2015 05:48:45 +0000 Message-ID: <1423288126-31119-5-git-send-email-viro@ZenIV.linux.org.uk> References: <20150207054419.GY29656@ZenIV.linux.org.uk> Cc: Christoph Hellwig , Miklos Szeredi , linux-aio@kvack.org, linux-fsdevel@vger.kernel.org, Felipe Balbi , linux-usb@vger.kernel.org, stable@vger.kernel.org To: Alan Stern Return-path: Received: from zeniv.linux.org.uk ([195.92.253.2]:57248 "EHLO ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751152AbbBGFst (ORCPT ); Sat, 7 Feb 2015 00:48:49 -0500 In-Reply-To: <20150207054419.GY29656@ZenIV.linux.org.uk> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: From: Al Viro 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 db49ec4..9fbbaa0 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 -- 2.1.4