From patchwork Tue Sep 15 03:41:18 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Nikunj A. Dadhania" X-Patchwork-Id: 264011 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=-12.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, 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 B6EBEC43461 for ; Tue, 15 Sep 2020 03:43:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7B7D0206E6 for ; Tue, 15 Sep 2020 03:43:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726120AbgIODni (ORCPT ); Mon, 14 Sep 2020 23:43:38 -0400 Received: from mga14.intel.com ([192.55.52.115]:17029 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726019AbgIODnh (ORCPT ); Mon, 14 Sep 2020 23:43:37 -0400 IronPort-SDR: SrTpG7h6dt36Eu3uZzYLJXXsnQHwiphOJwofuaaSIcmKdYz2g1l706CmuE7x/amndhqVh1Rxsw UKx4Z+/1ZO/g== X-IronPort-AV: E=McAfee;i="6000,8403,9744"; a="158479930" X-IronPort-AV: E=Sophos;i="5.76,428,1592895600"; d="scan'208";a="158479930" X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga004.fm.intel.com ([10.253.24.48]) by fmsmga103.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 14 Sep 2020 20:43:36 -0700 IronPort-SDR: tbHh1+mQ6HN95vTUK7Ea87D1JDw6r8GgQB9IwOI57BEOgLbPkft3yKO+Jz13vBAYzxFa/4TouK cCyPRIZGAb+w== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.76,428,1592895600"; d="scan'208";a="331008010" Received: from unknown (HELO ndadhani-NUC7i5BNKP.iind.intel.com) ([10.223.165.84]) by fmsmga004.fm.intel.com with ESMTP; 14 Sep 2020 20:43:33 -0700 From: "Nikunj A. Dadhania" To: intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, chris@chris-wilson.co.uk, Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , David Airlie , Daniel Vetter Cc: nikunj.dadhania@linux.intel.com, tvrtko.ursulin@intel.com, stable@vger.kernel.org Subject: [PATCH v2] drm/i915: Fix the race between the GEM close and debugfs Date: Tue, 15 Sep 2020 09:11:18 +0530 Message-Id: <20200915034118.32256-1-nikunj.dadhania@linux.intel.com> X-Mailer: git-send-email 2.17.1 Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org As we close GEM object and set file_priv to -EBADF which is protected by ctx->mutex, populating the GEM debugfs info is not protected and results in the crash shown below. Make sure to protect the access to file_priv using ctx->mutex to avoid race. BUG: unable to handle page fault for address: ffffffffffffffff RIP: 0010:i915_gem_object_info+0x26b/0x3eb Code: 89 44 24 48 48 89 44 24 40 48 89 44 24 38 48 89 44 24 30 48 89 44 24 28 48 89 44 24 20 49 8b 46 f0 48 89 44 24 20 49 8b 46 a0 <48> 8b 58 08 b9 0a 00 00 00 48 b8 aa aa aa aa aa aa aa aa 48 8d bc RSP: 0018:ffffac81c14cfc30 EFLAGS: 00010246 RAX: fffffffffffffff7 RBX: ffff95094429c218 RCX: ffff95096756c740 RDX: 0000000000000000 RSI: ffffffff919b93ee RDI: ffff95094429c218 RBP: ffffac81c14cfd58 R08: ffff9509746fab80 R09: 0000000000000000 R10: 0000000000000001 R11: 0000000000000000 R12: ffff9509753f8e80 R13: ffffac81c14cfc98 R14: ffff95094429c268 R15: ffffac81c14cfc88 FS: 00007a1bdcd52900(0000) GS:ffff950977e00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffffffffff CR3: 000000026b4e0000 CR4: 0000000000340ef0 Call Trace: seq_read+0x162/0x3ca full_proxy_read+0x5b/0x8d __vfs_read+0x45/0x1b9 vfs_read+0xc9/0x15e ksys_read+0x7e/0xde do_syscall_64+0x54/0x7e entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x7a1bdd34cf03 Signed-off-by: Nikunj A. Dadhania Reviewed-by: Tvrtko Ursulin Cc: stable@vger.kernel.org --- drivers/gpu/drm/i915/i915_debugfs.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_debugfs.c b/drivers/gpu/drm/i915/i915_debugfs.c index 784219962193..ea469168cd44 100644 --- 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 seq_file *m, } 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 seq_file *m, print_file_stats(m, name, stats); } + mutex_unlock(&ctx->mutex); spin_lock(&i915->gem.contexts.lock); list_safe_reset_next(ctx, cn, link);