From nobody Wed Sep 3 06:23:02 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4196EFA374B for ; Mon, 24 Oct 2022 12:35:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234593AbiJXMfb (ORCPT ); Mon, 24 Oct 2022 08:35:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51198 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234253AbiJXM3v (ORCPT ); Mon, 24 Oct 2022 08:29:51 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 41C6388DE2; Mon, 24 Oct 2022 05:03:48 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C893E61254; Mon, 24 Oct 2022 12:03:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id DC215C433C1; Mon, 24 Oct 2022 12:02:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666612980; bh=n5ji/6Rvcj9gwglRBVe1y6EZQDOybbfeuTH2XpQ1AzA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Ieo7OnM5vxPMFYRxU+LDs2kImRH7VWIxXYmLlC9prwHfbXbDlQQ6EfUSZSDoDngoK 1O6TPq0vIfkjWoDgtehX+7vpW/vGgaAB5aRVMwhFAxEMFhWRxR38pqhfQWkkY9USS/ rZft0JTE5pCR1gVudbRcQnHka/5MyiHGOaWgQnHI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Javier Martinez Canillas , Peter Robinson , Thomas Zimmermann , Sasha Levin Subject: [PATCH 4.19 193/229] drm: Use size_t type for len variable in drm_copy_field() Date: Mon, 24 Oct 2022 13:31:52 +0200 Message-Id: <20221024113005.372170248@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221024112959.085534368@linuxfoundation.org> References: <20221024112959.085534368@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" From: Javier Martinez Canillas [ Upstream commit 94dc3471d1b2b58b3728558d0e3f264e9ce6ff59 ] The strlen() function returns a size_t which is an unsigned int on 32-bit arches and an unsigned long on 64-bit arches. But in the drm_copy_field() function, the strlen() return value is assigned to an 'int len' variable. Later, the len variable is passed as copy_from_user() third argument that is an unsigned long parameter as well. In theory, this can lead to an integer overflow via type conversion. Since the assignment happens to a signed int lvalue instead of a size_t lvalue. In practice though, that's unlikely since the values copied are set by DRM drivers and not controlled by userspace. But using a size_t for len is the correct thing to do anyways. Signed-off-by: Javier Martinez Canillas Tested-by: Peter Robinson Reviewed-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20220705100215.572498-2= -javierm@redhat.com Signed-off-by: Sasha Levin --- drivers/gpu/drm/drm_ioctl.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index babd7ebabfef..4fea6519510c 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -458,7 +458,7 @@ EXPORT_SYMBOL(drm_invalid_op); */ static int drm_copy_field(char __user *buf, size_t *buf_len, const char *v= alue) { - int len; + size_t len; =20 /* don't overflow userbuf */ len =3D strlen(value); --=20 2.35.1