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 B4D2E429838; Thu, 30 Apr 2026 14:01:52 +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=1777557712; cv=none; b=sbCZ/6Z2SKgV5GeQjmsQNLKElfXWDdIwaoPaQhR8Ynb1GHZ+r6eNFjcBYNhqlfndIiPw5UxvXAGZ6HeZXJ4Mb26wSfIZlMLPNFpHEDi9Nd0+lJzoOJfadeVeRxVU/BpfyBZMIOv95qsFJbUd89E93BFK9kyo/oZGU+keNrn3tzU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777557712; c=relaxed/simple; bh=iJvrnpEDdabxjvqrmpL8gz3s1M//If/CvWBRLaxnlgk=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pG22zmTl6aqBsoEYJVx+9ohrpPLpO2sC+vjSsxRhQxtCQLCXAex/lWBeI7xvApPa6QtH/Piseu4GP6xu09krDHtSujOowSp30gYjFyfJbnQE/G8IndKlgL76nofnTz1wrmMzdtyfjgYPuU+P7oy8u9agoRTSWELjfUvep8E5tpc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=kttA5e2G; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="kttA5e2G" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D91C7C2BCB3; Thu, 30 Apr 2026 14:01:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1777557712; bh=iJvrnpEDdabxjvqrmpL8gz3s1M//If/CvWBRLaxnlgk=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=kttA5e2GJQHTdlJBo7pmJN1hw+ib6J6rXs9YIzFtXQvaLcMhGY5Rk8W2s0P+vnNnE 9UkDRcefAy0m4Q/z4GbeZqDjV1OFiEO+fr1IXIiG7AFNGnkopf55plUY+H2ETUjKLA smPcy1lNHpeofSeo3OGeVYN0kw9xhAUL9hA9BRs67FdwOIw4N778J3CbV/OEFybAYh 4gwD0+s/skxICg7sNFwLOp/YWKUrjA2w2lGh6BnMgKGQH7fqpVmmgk8fJv2NuGN0sw WxS+SKr0XypBsG+gKD9hJ2tB6aWnAqdHQ/9Lq6ReZW6x5GcLqPH3irs383EV6iSXIB t7CLpf0gCbkMQ== Date: Thu, 30 Apr 2026 15:01:48 +0100 From: Lee Jones To: =?iso-8859-1?Q?G=FCnther?= Noack Cc: Jiri Kosina , Benjamin Tissoires , linux-input@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 1/1] HID: magicmouse: Prevent out-of-bounds (OOB) read during DOUBLE_REPORT_ID Message-ID: <20260430140148.GJ1806155@google.com> References: <20260416131655.2279756-1-lee@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Thu, 16 Apr 2026, Günther Noack wrote: > On Thu, Apr 16, 2026 at 02:16:54PM +0100, Lee Jones wrote: > > It is currently possible for a malicious or misconfigured USB device to > > cause an out-of-bounds (OOB) read when submitting reports using > > DOUBLE_REPORT_ID by specifying a large report length and providing a > > smaller one. > > > > Let's prevent that by comparing the specified report length with the > > actual size of the data read in from userspace. If the actual data > > length ends up being smaller than specified, we'll politely warn the > > user and prevent any further processing. > > > > Signed-off-by: Lee Jones > > --- > > v1 => v2: Add more size checks to protect against issues during recursion > > > > drivers/hid/hid-magicmouse.c | 16 ++++++++++++++++ > > 1 file changed, 16 insertions(+) > > > > diff --git a/drivers/hid/hid-magicmouse.c b/drivers/hid/hid-magicmouse.c > > index 91f621ceb924..e84e6b21d113 100644 > > --- a/drivers/hid/hid-magicmouse.c > > +++ b/drivers/hid/hid-magicmouse.c > > @@ -390,6 +390,10 @@ static int magicmouse_raw_event(struct hid_device *hdev, > > struct input_dev *input = msc->input; > > int x = 0, y = 0, ii, clicks = 0, npoints; > > > > + /* Protect against zero sized recursive calls from DOUBLE_REPORT_ID */ > > + if (size < 1) > > + return 0; > > + > > switch (data[0]) { > > case TRACKPAD_REPORT_ID: > > case TRACKPAD2_BT_REPORT_ID: > > @@ -490,6 +494,18 @@ static int magicmouse_raw_event(struct hid_device *hdev, > > /* Sometimes the trackpad sends two touch reports in one > > * packet. > > */ > > + > > + /* Ensure that we have at least 2 elements (report type and size) */ > > + if (size < 2) > > + return 0; > > + > > + if (size < data[1] + 2) { > > + hid_warn(hdev, > > + "received report length (%d) was smaller than specified (%d)", > > + size, data[1] + 2); > > + return 0; > > + } > > + > > magicmouse_raw_event(hdev, report, data + 2, data[1]); > > magicmouse_raw_event(hdev, report, data + 2 + data[1], > > size - 2 - data[1]); > > -- > > 2.54.0.rc1.513.gad8abe7a5a-goog > > > > Thank you! This looks correct now. > > Reviewed-by: Günther Noack Contentless ping. =:-) -- Lee Jones