From nobody Sun Sep 14 16:12:22 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 38BFCC004D4 for ; Thu, 19 Jan 2023 17:33:27 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229760AbjASRd0 (ORCPT ); Thu, 19 Jan 2023 12:33:26 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41412 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229688AbjASRdW (ORCPT ); Thu, 19 Jan 2023 12:33:22 -0500 Received: from mail-pj1-x1035.google.com (mail-pj1-x1035.google.com [IPv6:2607:f8b0:4864:20::1035]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DE01B48A05 for ; Thu, 19 Jan 2023 09:33:20 -0800 (PST) Received: by mail-pj1-x1035.google.com with SMTP id z9-20020a17090a468900b00226b6e7aeeaso2473433pjf.1 for ; Thu, 19 Jan 2023 09:33:20 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=LPLlNSnzLIud/SdIjCx832sULylUvnbc8QUJ7Ss0K9I=; b=k1cvGWKFMNGBv17/1p6v1IzvK0wT7IqiQaY0qVkC9tFtXwvnQeVPQI2Ave2sLVk2e0 MfuORfn+YssgcdOkxHddBrrGWaafBL5IURnRtFlvY+e5+W4Og+ghhiUHLxN4jjdybZKd FTeoilFVWhfnfVDBFSUBRG0PTbJLHyco19q4i/XPJ48+lVMv3yAtRMr/YaPoKBbjGOhr 5r5sfXajaygIY7QmIfKP9AM0yOgw+qMvcpeb6kxlZbXJ7cxkoupDp3VMRiLePsuT87AT IVokInBr9wvB6h6eApokTwZZ5nH2Br01Jrkn5i6jgjOiJE0U4l0EnAWYj1t5TRUonDU0 l/oQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=LPLlNSnzLIud/SdIjCx832sULylUvnbc8QUJ7Ss0K9I=; b=epdlO0afnMiFy00g3JAu/tYKds1mvb6ZhsoPd4Cfzz2p0C9/imUU/pDUMyjYV/eUfi 2OvUe19X88kxnyoLztgATycVjZ8TG9wYC0aMQZ1n8I9LQ/PlU5hmGU7UdMdl5DrcGGtj PR+Uc4fbSOEgPHkoiBeTSl7ztNJEIEsU7Nnxs5MxWmjFFijxqKtzS0+LsYuMR7cakjzw 1demIv8FNGwRrl+HrBh5/djO22zTNngpj0n0pTDZR8YvUy0RJ38lOJGTBxNhS99I28Lw Mvqf48QCMb1PlxkYHau5ZIZ19I4+ud1b23W5fHivh3S9puuOAOq5CcMhosKqqZ5FMdck q87A== X-Gm-Message-State: AFqh2koPct4hr9PfHGtYJHTZ+39OFzb278KEjWcSbyyeKYYRUFeDCIQS DdgO99eXTrs9/AoNOPk3V1c= X-Google-Smtp-Source: AMrXdXv2qS952OsbhGL/YPtOfwGxEviqVp97NLihSuTFSqNi0Ri2Pdr4RxBMsphukL35cOs0qRhcEA== X-Received: by 2002:a05:6a20:d045:b0:ac:3f3f:9fbd with SMTP id hv5-20020a056a20d04500b000ac3f3f9fbdmr13438174pzb.48.1674149600323; Thu, 19 Jan 2023 09:33:20 -0800 (PST) Received: from localhost ([2a00:79e1:abd:4a00:2703:3c72:eb1a:cffd]) by smtp.gmail.com with ESMTPSA id k36-20020a635a64000000b0048988ed9e4bsm20523336pgm.19.2023.01.19.09.33.19 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 19 Jan 2023 09:33:19 -0800 (PST) From: Rob Clark To: dri-devel@lists.freedesktop.org Cc: Tvrtko Ursulin , Rob Clark , Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie , Daniel Vetter , Chris Wilson , Andi Shyti , John Harrison , Matthew Brost , katrinzhou , =?UTF-8?q?Thomas=20Hellstr=C3=B6m?= , intel-gfx@lists.freedesktop.org, linux-kernel@vger.kernel.org (open list) Subject: [PATCH] drm/i915: Avoid potential vm use-after-free Date: Thu, 19 Jan 2023 09:32:58 -0800 Message-Id: <20230119173321.2825472-1-robdclark@gmail.com> X-Mailer: git-send-email 2.38.1 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: Rob Clark Adding the vm to the vm_xa table makes it visible to userspace, which could try to race with us to close the vm. So we need to take our extra reference before putting it in the table. Signed-off-by: Rob Clark Reviewed-by: Matthew Auld --- Note, you could list commit e1a7ab4fca0c ("drm/i915: Remove the vm open count") as the "fixed" commit, but really the issue seems to go back much further (with the fix needing some backporting in the process). drivers/gpu/drm/i915/gem/i915_gem_context.c | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/= i915/gem/i915_gem_context.c index 6250de9b9196..e4b78ab4773b 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c @@ -1861,11 +1861,19 @@ static int get_ppgtt(struct drm_i915_file_private *= file_priv, vm =3D ctx->vm; GEM_BUG_ON(!vm); =20 + /* + * Get a reference for the allocated handle. Once the handle is + * visible in the vm_xa table, userspace could try to close it + * from under our feet, so we need to hold the extra reference + * first. + */ + i915_vm_get(vm); + err =3D xa_alloc(&file_priv->vm_xa, &id, vm, xa_limit_32b, GFP_KERNEL); - if (err) + if (err) { + i915_vm_put(vm); return err; - - i915_vm_get(vm); + } =20 GEM_BUG_ON(id =3D=3D 0); /* reserved for invalid/unassigned ppgtt */ args->value =3D id; --=20 2.38.1