From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 72750145A05 for ; Fri, 28 Mar 2025 21:04:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743195850; cv=none; b=Nf3qlVORHWocglM8NV66tpppxGJOocQHGFx1Rsw1EkoT/MPcC/QJVory6kv+GC9LbUWvS7yWkly6xqWmEMSlvQ/m8sh2cNYeN6KgjSBF134Vrv/ly2dT+nMrkSOr4eUaSsldhxL0Ee5WdtnJBCwaOekYRfqWFRbJ7XG3Pcf/nMI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1743195850; c=relaxed/simple; bh=vtWvm+/AzPp+LBBJt3DZR5sLduYGjNj5H2sVIh2rXd0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=KxuMXliuVSKTWL9kLND3WdH3CCm3w1lTE6B77cnLJKq/03kXDxJUeauSpm/XMoALk+V081V8XVhDon0tfUjYxJNi2kD6Rdf7C7RuDPBEssybHPCPtXQCxXPj1q8zvcW6yTq22ZS/+wMk82jo40IUEuQiTiHf3EnYoBvHcPyV8so= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=Dfg2aF5A; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="Dfg2aF5A" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 8AD49C4CEE4; Fri, 28 Mar 2025 21:04:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1743195849; bh=vtWvm+/AzPp+LBBJt3DZR5sLduYGjNj5H2sVIh2rXd0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=Dfg2aF5AgHdXzOpMKyojLPn4u4fe9sgisFYgku3u3+V5SgcrHObytERzIoCYo8vmj 40ThXKLV1vLTx/p8RstPwYc5K+FvjOdgUlM5jTIVOvjn3iTpYOkYZK/MIeOGv3cVsC toMqITQD8XHkr3lLpF36PnHZwq4fh16e/Qj66QLE= Date: Fri, 28 Mar 2025 22:02:45 +0100 From: Greg KH To: Frode Isaksen Cc: linux-usb@vger.kernel.org, Thinh.Nguyen@synopsys.com, Frode Isaksen Subject: Re: [PATCH] usb: gadget: f_fs: Invalidate io_data when USB request is dequeued or completed Message-ID: <2025032835-sixtieth-unable-1548@gregkh> References: <20250328161823.2240125-1-fisaksen@baylibre.com> Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250328161823.2240125-1-fisaksen@baylibre.com> On Fri, Mar 28, 2025 at 05:17:15PM +0100, Frode Isaksen wrote: > From: Frode Isaksen > > Invalidate io_data by setting context to NULL when USB request is > dequeued or completed, and check for NULL io_data in epfile_io_complete(). > The invalidation of io_data in req->context is done when exiting > epfile_io(), since then io_data will become invalid as it is allocated > on the stack. > The epfile_io_complete() may be called after ffs_epfile_io() returns > in case the wait_for_completion_interruptible() is interrupted. > This fixes a use-after-free error with the following call stack: > > Unable to handle kernel paging request at virtual address ffffffc02f7bbcc0 > pc : ffs_epfile_io_complete+0x30/0x48 > lr : usb_gadget_giveback_request+0x30/0xf8 > Call trace: > ffs_epfile_io_complete+0x30/0x48 > usb_gadget_giveback_request+0x30/0xf8 > dwc3_remove_requests+0x264/0x2e8 > dwc3_gadget_pullup+0x1d0/0x250 > kretprobe_trampoline+0x0/0xc4 > usb_gadget_remove_driver+0x40/0xf4 > usb_gadget_unregister_driver+0xdc/0x178 > unregister_gadget_item+0x40/0x6c > ffs_closed+0xd4/0x10c > ffs_data_clear+0x2c/0xf0 > ffs_data_closed+0x178/0x1ec > ffs_ep0_release+0x24/0x38 > __fput+0xe8/0x27c > > Signed-off-by: Frode Isaksen > --- > This bug was discovered, tested and fixed (no more crashes seen) on Meta Quest 3 device. > Also tested on T.I. AM62x board. What commit id does this fix? Should it go to stable? > > drivers/usb/gadget/function/f_fs.c | 5 +++++ > 1 file changed, 5 insertions(+) > > diff --git a/drivers/usb/gadget/function/f_fs.c b/drivers/usb/gadget/function/f_fs.c > index 2dea9e42a0f8..f1be0a5c0bd0 100644 > --- a/drivers/usb/gadget/function/f_fs.c > +++ b/drivers/usb/gadget/function/f_fs.c > @@ -738,6 +738,9 @@ static void ffs_epfile_io_complete(struct usb_ep *_ep, struct usb_request *req) > { > struct ffs_io_data *io_data = req->context; > > + if (WARN_ON(io_data == NULL)) > + return; If this happens you just crashed the box (remember about panic-on-warn, which is still set in a few billion Linux systems these days...) Just handle the issue properly, no need to dump the stack and crash a device. But, what keeps io_data from changing after you have checked it? Where is the lock here? thanks, greg k-h