From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753127AbdBTKZo (ORCPT ); Mon, 20 Feb 2017 05:25:44 -0500 Received: from mga11.intel.com ([192.55.52.93]:44033 "EHLO mga11.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753039AbdBTKZk (ORCPT ); Mon, 20 Feb 2017 05:25:40 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.35,186,1484035200"; d="scan'208";a="935966932" From: Elena Reshetova To: linux-kernel@vger.kernel.org Cc: cgroups@vger.kernel.org, linux-audit@redhat.com, linux-fsdevel@vger.kernel.org, peterz@infradead.org, gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk, tj@kernel.org, mingo@redhat.com, hannes@cmpxchg.org, lizefan@huawei.com, acme@kernel.org, alexander.shishkin@linux.intel.com, paul@paul-moore.com, eparis@redhat.com, akpm@linux-foundation.org, arnd@arndb.de, luto@kernel.org, Elena Reshetova , Hans Liljestrand , Kees Cook , David Windsor Subject: [PATCH 18/19] kernel: convert futex_pi_state.refcount from atomic_t to refcount_t Date: Mon, 20 Feb 2017 12:19:07 +0200 Message-Id: <1487585948-6401-19-git-send-email-elena.reshetova@intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1487585948-6401-1-git-send-email-elena.reshetova@intel.com> References: <1487585948-6401-1-git-send-email-elena.reshetova@intel.com> 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. Signed-off-by: Elena Reshetova Signed-off-by: Hans Liljestrand Signed-off-by: Kees Cook Signed-off-by: David Windsor --- kernel/futex.c | 15 ++++++++------- 1 file changed, 8 insertions(+), 7 deletions(-) diff --git a/kernel/futex.c b/kernel/futex.c index b687cb2..4ef9c10 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -65,6 +65,7 @@ #include #include #include +#include #include @@ -207,7 +208,7 @@ struct futex_pi_state { struct rt_mutex pi_mutex; struct task_struct *owner; - atomic_t refcount; + refcount_t refcount; union futex_key key; }; @@ -792,7 +793,7 @@ static int refill_pi_state_cache(void) INIT_LIST_HEAD(&pi_state->list); /* pi_mutex gets initialized later */ pi_state->owner = NULL; - atomic_set(&pi_state->refcount, 1); + refcount_set(&pi_state->refcount, 1); pi_state->key = FUTEX_KEY_INIT; current->pi_state_cache = pi_state; @@ -821,7 +822,7 @@ static void put_pi_state(struct futex_pi_state *pi_state) if (!pi_state) return; - if (!atomic_dec_and_test(&pi_state->refcount)) + if (!refcount_dec_and_test(&pi_state->refcount)) return; /* @@ -845,7 +846,7 @@ static void put_pi_state(struct futex_pi_state *pi_state) * refcount is at 0 - put it back to 1. */ pi_state->owner = NULL; - atomic_set(&pi_state->refcount, 1); + refcount_set(&pi_state->refcount, 1); current->pi_state_cache = pi_state; } } @@ -989,7 +990,7 @@ static int attach_to_pi_state(u32 uval, struct futex_pi_state *pi_state, if (unlikely(!pi_state)) return -EINVAL; - WARN_ON(!atomic_read(&pi_state->refcount)); + WARN_ON(!refcount_read(&pi_state->refcount)); /* * Handle the owner died case: @@ -1040,7 +1041,7 @@ static int attach_to_pi_state(u32 uval, struct futex_pi_state *pi_state, if (pid != task_pid_vnr(pi_state->owner)) return -EINVAL; out_state: - atomic_inc(&pi_state->refcount); + refcount_inc(&pi_state->refcount); *ps = pi_state; return 0; } @@ -1907,7 +1908,7 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags, * refcount on the pi_state and store the pointer in * the futex_q object of the waiter. */ - atomic_inc(&pi_state->refcount); + refcount_inc(&pi_state->refcount); this->pi_state = pi_state; ret = rt_mutex_start_proxy_lock(&pi_state->pi_mutex, this->rt_waiter, -- 2.7.4