From mboxrd@z Thu Jan 1 00:00:00 1970 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 49AA1C388F9 for ; Sat, 31 Oct 2020 11:42:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 17BD6206D5 for ; Sat, 31 Oct 2020 11:42:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604144558; bh=hBXHsYZ6myK5Hnhs1bJ2kqbSzt3r4kUKTX4lwf4DFIM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=cIMxgVHSrs1Cd7ufHecauZC3fzaUC1MIQAKJzApLP8DixacXvXtHL/yY2oBETSyB1 FEFef9xN7QhafBV+gRxg1u3XqCpcJ1lwW/yWn5nXE0P/BZ26ObbKkqWgqSmkceTRCL fkfxqr3Yyczbt0LAThvqxS9uG0VY9Em36fl4CHtw= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727890AbgJaLmf (ORCPT ); Sat, 31 Oct 2020 07:42:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:42126 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727865AbgJaLmc (ORCPT ); Sat, 31 Oct 2020 07:42:32 -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 14514205F4; Sat, 31 Oct 2020 11:42:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1604144551; bh=hBXHsYZ6myK5Hnhs1bJ2kqbSzt3r4kUKTX4lwf4DFIM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SuY1Pw6tugFlcoHoCa3LEttZqmsQ3HJTtUpZDtGRM+6N/KhHlQ7h+e4ArpV6zV55o UuyVSguxckXNO+5c6qypnvu2podq4K1EhZKJUOQXG2SBKQirBE/kYt+L6DWSWHQFrY Sap8SP5R7/8crZ8AiCGd49CH3x+gPAZtgDlqGWIs= 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 5.8 62/70] drm/i915/gem: Serialise debugfs i915_gem_objects with ctx->mutex Date: Sat, 31 Oct 2020 12:36:34 +0100 Message-Id: <20201031113502.462944295@linuxfoundation.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20201031113459.481803250@linuxfoundation.org> References: <20201031113459.481803250@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@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 @@ -323,6 +323,7 @@ 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), @@ -343,6 +344,7 @@ 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);