From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S946043AbdDTNjN (ORCPT ); Thu, 20 Apr 2017 09:39:13 -0400 Received: from mga06.intel.com ([134.134.136.31]:37211 "EHLO mga06.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S945907AbdDTNjK (ORCPT ); Thu, 20 Apr 2017 09:39:10 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.37,225,1488873600"; d="scan'208";a="76746426" From: Elena Reshetova To: bp@alien8.de Cc: linux-kernel@vger.kernel.org, dwindsor@gmail.com, ishkamiel@gmail.com, keescook@chromium.org, Elena Reshetova Subject: [PATCH] x86: convert threshold_bank.cpus from atomic_t to refcount_t Date: Thu, 20 Apr 2017 16:38:56 +0300 Message-Id: <1492695536-5947-1-git-send-email-elena.reshetova@intel.com> X-Mailer: git-send-email 2.7.4 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations. Suggested-by: Kees Cook Signed-off-by: Elena Reshetova Reviewed-by: Hans Liljestrand Reviewed-by: David Windsor --- arch/x86/include/asm/amd_nb.h | 3 ++- arch/x86/kernel/cpu/mcheck/mce_amd.c | 6 +++--- 2 files changed, 5 insertions(+), 4 deletions(-) diff --git a/arch/x86/include/asm/amd_nb.h b/arch/x86/include/asm/amd_nb.h index 00c88a0..da181ad 100644 --- a/arch/x86/include/asm/amd_nb.h +++ b/arch/x86/include/asm/amd_nb.h @@ -3,6 +3,7 @@ #include #include +#include struct amd_nb_bus_dev_range { u8 bus; @@ -55,7 +56,7 @@ struct threshold_bank { struct threshold_block *blocks; /* initialized to the number of CPUs on the node sharing this bank */ - atomic_t cpus; + refcount_t cpus; }; struct amd_northbridge { diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd.c b/arch/x86/kernel/cpu/mcheck/mce_amd.c index 524cc57..cfe0838 100644 --- a/arch/x86/kernel/cpu/mcheck/mce_amd.c +++ b/arch/x86/kernel/cpu/mcheck/mce_amd.c @@ -1202,7 +1202,7 @@ static int threshold_create_bank(unsigned int cpu, unsigned int bank) goto out; per_cpu(threshold_banks, cpu)[bank] = b; - atomic_inc(&b->cpus); + refcount_inc(&b->cpus); err = __threshold_add_blocks(b); @@ -1225,7 +1225,7 @@ static int threshold_create_bank(unsigned int cpu, unsigned int bank) per_cpu(threshold_banks, cpu)[bank] = b; if (is_shared_bank(bank)) { - atomic_set(&b->cpus, 1); + refcount_set(&b->cpus, 1); /* nb is already initialized, see above */ if (nb) { @@ -1289,7 +1289,7 @@ static void threshold_remove_bank(unsigned int cpu, int bank) goto free_out; if (is_shared_bank(bank)) { - if (!atomic_dec_and_test(&b->cpus)) { + if (!refcount_dec_and_test(&b->cpus)) { __threshold_remove_blocks(b); per_cpu(threshold_banks, cpu)[bank] = NULL; return; -- 2.7.4