From patchwork Sat Oct 31 11:36:47 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 317381 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED, DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AECF3C388F7 for ; Sat, 31 Oct 2020 11:47:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 73C4420691 for ; Sat, 31 Oct 2020 11:47:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604144838; bh=ctsLQX4IzMaqnIkJTWQaiEYWDwWFei5c4q8S7N7vulI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=LEEDWKmuAXZDQPR5UBhxxlqVttQ2Pt8KWAcPH5sdtFcUxnfGmpGT2j+r4CwEUpoqg PNj2k3r6pRI3nYCfXqwej0pEzGEbHa+8TWxRS8OBALi4c8RqraZg4xWQ9NseVxv6Iv eqhY3qsTYkM2oKTkYNZbOyemwXp424eV4BrRxXP4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727037AbgJaLrR (ORCPT ); Sat, 31 Oct 2020 07:47:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:46808 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728299AbgJaLpq (ORCPT ); Sat, 31 Oct 2020 07:45:46 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 3BF8B20731; Sat, 31 Oct 2020 11:45:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604144744; bh=ctsLQX4IzMaqnIkJTWQaiEYWDwWFei5c4q8S7N7vulI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GhFdkMCsVlVf0VALanrg5H9ggU+JE/JkF/1ClbI6RhANc/ZdtL/YZAVYKNERiuoPg RibEvW6nuMIFEZulFo/NFfdV4Of7sqXsMBabiewdYtLbQw+JIA2X2YF3RWb6gMhb6H LDqwzW2Dy2IbRfL04OtFpmA7G9uPc1encyFz0HxU= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Chris Wilson , CQ Tang , Daniel Vetter , Tvrtko Ursulin , Rodrigo Vivi Subject: [PATCH 5.9 65/74] drm/i915/gem: Serialise debugfs i915_gem_objects with ctx->mutex Date: Sat, 31 Oct 2020 12:36:47 +0100 Message-Id: <20201031113503.143529242@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201031113500.031279088@linuxfoundation.org> References: <20201031113500.031279088@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Chris Wilson commit 4fe9af8e881d946bf60790eeb37a7c4f96e28382 upstream. Since the debugfs may peek into the GEM contexts as the corresponding client/fd is being closed, we may try and follow a dangling pointer. However, the context closure itself is serialised with the ctx->mutex, so if we hold that mutex as we inspect the state coupled in the context, we know the pointers within the context are stable and will remain valid as we inspect their tables. Signed-off-by: Chris Wilson Cc: CQ Tang Cc: Daniel Vetter Cc: stable@vger.kernel.org Reviewed-by: Tvrtko Ursulin Link: https://patchwork.freedesktop.org/patch/msgid/20200723172119.17649-3-chris@chris-wilson.co.uk (cherry picked from commit 102f5aa491f262c818e607fc4fee08a724a76c69) Signed-off-by: Rodrigo Vivi Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/i915/i915_debugfs.c | 2 ++ 1 file changed, 2 insertions(+) --- a/drivers/gpu/drm/i915/i915_debugfs.c +++ b/drivers/gpu/drm/i915/i915_debugfs.c @@ -326,6 +326,7 @@ static void print_context_stats(struct s } i915_gem_context_unlock_engines(ctx); + mutex_lock(&ctx->mutex); if (!IS_ERR_OR_NULL(ctx->file_priv)) { struct file_stats stats = { .vm = rcu_access_pointer(ctx->vm), @@ -346,6 +347,7 @@ static void print_context_stats(struct s print_file_stats(m, name, stats); } + mutex_unlock(&ctx->mutex); spin_lock(&i915->gem.contexts.lock); list_safe_reset_next(ctx, cn, link);