From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965751AbcKLBDW (ORCPT ); Fri, 11 Nov 2016 20:03:22 -0500 Received: from mga11.intel.com ([192.55.52.93]:7540 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933992AbcKLBDV (ORCPT ); Fri, 11 Nov 2016 20:03:21 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.31,475,1473145200"; d="scan'208";a="1058482005" From: "Fenghua Yu" To: "Thomas Gleixner" Cc: "H. Peter Anvin" , "Ingo Molnar" , "Tony Luck" , "Ravi V Shankar" , "Sai Prakhya" , "Vikas Shivappa" , "linux-kernel" , "x86" , "Fenghua Yu" Subject: [PATCH 1/3] x86/intel_rdt: Fix kernfs_to_rdtgroup to know about "info/*" directories Date: Fri, 11 Nov 2016 17:02:36 -0800 Message-Id: <1478912558-55514-1-git-send-email-fenghua.yu@intel.com> X-Mailer: git-send-email 1.8.0.1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Fenghua Yu We saw a kernel oops on NULL pointer when we ran "rmdir info". This is because the "info" directory and per-resource subdirectories of "info" do not use "kn->priv" to point to a "struct rdtgroup". Also change error code from -ENOENT to the more appropriate -EPERM so the user sees "Operation not permitted". Signed-off-by: Fenghua Yu --- arch/x86/kernel/cpu/intel_rdt_rdtgroup.c | 24 ++++++++++++++++++++---- 1 file changed, 20 insertions(+), 4 deletions(-) diff --git a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c index 4795880..cff286e 100644 --- a/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c +++ b/arch/x86/kernel/cpu/intel_rdt_rdtgroup.c @@ -644,16 +644,29 @@ static int parse_rdtgroupfs_options(char *data) */ static struct rdtgroup *kernfs_to_rdtgroup(struct kernfs_node *kn) { - if (kernfs_type(kn) == KERNFS_DIR) - return kn->priv; - else + if (kernfs_type(kn) == KERNFS_DIR) { + /* + * All the resource directories use "kn->priv" + * to point to the "struct rdtgroup" for the + * resource. "info" and its subdirectories don't + * have rdtgroup structures, so return NULL here. + */ + if (kn == kn_info || kn->parent == kn_info) + return NULL; + else + return kn->priv; + } else { return kn->parent->priv; + } } struct rdtgroup *rdtgroup_kn_lock_live(struct kernfs_node *kn) { struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn); + if (!rdtgrp) + return NULL; + atomic_inc(&rdtgrp->waitcount); kernfs_break_active_protection(kn); @@ -670,6 +683,9 @@ void rdtgroup_kn_unlock(struct kernfs_node *kn) { struct rdtgroup *rdtgrp = kernfs_to_rdtgroup(kn); + if (!rdtgrp) + return; + mutex_unlock(&rdtgroup_mutex); if (atomic_dec_and_test(&rdtgrp->waitcount) && @@ -918,7 +934,7 @@ static int rdtgroup_rmdir(struct kernfs_node *kn) rdtgrp = rdtgroup_kn_lock_live(kn); if (!rdtgrp) { rdtgroup_kn_unlock(kn); - return -ENOENT; + return -EPERM; } /* Give any tasks back to the default group */ -- 2.5.0