From nobody Wed Sep 3 06:46:55 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 AD74EFA3757 for ; Mon, 24 Oct 2022 16:51:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235198AbiJXQvJ (ORCPT ); Mon, 24 Oct 2022 12:51:09 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36304 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233678AbiJXQrk (ORCPT ); Mon, 24 Oct 2022 12:47:40 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F0C97169105; Mon, 24 Oct 2022 08:31:41 -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 ams.source.kernel.org (Postfix) with ESMTPS id 53450B811AC; Mon, 24 Oct 2022 12:03:04 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7F073C433C1; Mon, 24 Oct 2022 12:03:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666612983; bh=uh4tAMinP/rEAHn+FCntp1011ta1Ubrk3F2gTJ+r6pA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IXzBPHLHUYY55FqLbPoS7M4LtnAmn6FdBV/mrB6QyrWWWyalFns247gwQ8u+GsWye kbOKcDTF8ayzSW5SZvfHwATSLTfo4a20DiR329OGC/CbY80nmbVg16LgjvRyn01+ZN CqlAC2sc7XXi3IFSb89ajz802j+9wiZzs2beP3Co= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Peter Robinson , Javier Martinez Canillas , Thomas Zimmermann , Sasha Levin Subject: [PATCH 4.19 194/229] drm: Prevent drm_copy_field() to attempt copying a NULL pointer Date: Mon, 24 Oct 2022 13:31:53 +0200 Message-Id: <20221024113005.400833863@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 f6ee30407e883042482ad4ad30da5eaba47872ee ] There are some struct drm_driver fields that are required by drivers since drm_copy_field() attempts to copy them to user-space via DRM_IOCTL_VERSION. But it can be possible that a driver has a bug and did not set some of the fields, which leads to drm_copy_field() attempting to copy a NULL pointer: [ +10.395966] Unable to handle kernel access to user memory outside uaccess= routines at virtual address 0000000000000000 [ +0.010955] Mem abort info: [ +0.002835] ESR =3D 0x0000000096000004 [ +0.003872] EC =3D 0x25: DABT (current EL), IL =3D 32 bits [ +0.005395] SET =3D 0, FnV =3D 0 [ +0.003113] EA =3D 0, S1PTW =3D 0 [ +0.003182] FSC =3D 0x04: level 0 translation fault [ +0.004964] Data abort info: [ +0.002919] ISV =3D 0, ISS =3D 0x00000004 [ +0.003886] CM =3D 0, WnR =3D 0 [ +0.003040] user pgtable: 4k pages, 48-bit VAs, pgdp=3D0000000115dad000 [ +0.006536] [0000000000000000] pgd=3D0000000000000000, p4d=3D000000000000= 0000 [ +0.006925] Internal error: Oops: 96000004 [#1] SMP ... [ +0.011113] pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE= =3D--) [ +0.007061] pc : __pi_strlen+0x14/0x150 [ +0.003895] lr : drm_copy_field+0x30/0x1a4 [ +0.004156] sp : ffff8000094b3a50 [ +0.003355] x29: ffff8000094b3a50 x28: ffff8000094b3b70 x27: 000000000000= 0040 [ +0.007242] x26: ffff443743c2ba00 x25: 0000000000000000 x24: 000000000000= 0040 [ +0.007243] x23: ffff443743c2ba00 x22: ffff8000094b3b70 x21: 000000000000= 0000 [ +0.007241] x20: 0000000000000000 x19: ffff8000094b3b90 x18: 000000000000= 0000 [ +0.007241] x17: 0000000000000000 x16: 0000000000000000 x15: 0000aaab14b9= af40 [ +0.007241] x14: 0000000000000000 x13: 0000000000000000 x12: 000000000000= 0000 [ +0.007239] x11: 0000000000000000 x10: 0000000000000000 x9 : ffffa524ad67= d4d8 [ +0.007242] x8 : 0101010101010101 x7 : 7f7f7f7f7f7f7f7f x6 : 6c6e6263606e= 7141 [ +0.007239] x5 : 0000000000000000 x4 : 0000000000000000 x3 : 000000000000= 0000 [ +0.007241] x2 : 0000000000000000 x1 : ffff8000094b3b90 x0 : 000000000000= 0000 [ +0.007240] Call trace: [ +0.002475] __pi_strlen+0x14/0x150 [ +0.003537] drm_version+0x84/0xac [ +0.003448] drm_ioctl_kernel+0xa8/0x16c [ +0.003975] drm_ioctl+0x270/0x580 [ +0.003448] __arm64_sys_ioctl+0xb8/0xfc [ +0.003978] invoke_syscall+0x78/0x100 [ +0.003799] el0_svc_common.constprop.0+0x4c/0xf4 [ +0.004767] do_el0_svc+0x38/0x4c [ +0.003357] el0_svc+0x34/0x100 [ +0.003185] el0t_64_sync_handler+0x11c/0x150 [ +0.004418] el0t_64_sync+0x190/0x194 [ +0.003716] Code: 92402c04 b200c3e8 f13fc09f 5400088c (a9400c02) [ +0.006180] ---[ end trace 0000000000000000 ]--- Reported-by: Peter Robinson Signed-off-by: Javier Martinez Canillas Acked-by: Thomas Zimmermann Link: https://patchwork.freedesktop.org/patch/msgid/20220705100215.572498-3= -javierm@redhat.com Signed-off-by: Sasha Levin --- drivers/gpu/drm/drm_ioctl.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c index 4fea6519510c..2651bfb763a4 100644 --- a/drivers/gpu/drm/drm_ioctl.c +++ b/drivers/gpu/drm/drm_ioctl.c @@ -460,6 +460,12 @@ static int drm_copy_field(char __user *buf, size_t *bu= f_len, const char *value) { size_t len; =20 + /* don't attempt to copy a NULL pointer */ + if (WARN_ONCE(!value, "BUG: the value to copy was not set!")) { + *buf_len =3D 0; + return 0; + } + /* don't overflow userbuf */ len =3D strlen(value); if (len > *buf_len) --=20 2.35.1