From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: 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 12/19] kernel: convert css_set.refcount from atomic_t to refcount_t Date: Mon, 20 Feb 2017 12:19:01 +0200 Message-Id: <1487585948-6401-13-git-send-email-elena.reshetova@intel.com> 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: 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 --- include/linux/cgroup-defs.h | 3 ++- kernel/cgroup/cgroup-internal.h | 10 +++++++--- kernel/cgroup/cgroup-v1.c | 4 ++-- kernel/cgroup/cgroup.c | 8 ++++---- 4 files changed, 15 insertions(+), 10 deletions(-) diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 3c02404..e2f4b31 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -13,6 +13,7 @@ #include #include #include +#include #include #include #include @@ -156,7 +157,7 @@ struct css_set { struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; /* reference count */ - atomic_t refcount; + refcount_t refcount; /* the default cgroup associated with this css_set */ struct cgroup *dfl_cgrp; diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h index 9203bfb..22d87ca 100644 --- a/kernel/cgroup/cgroup-internal.h +++ b/kernel/cgroup/cgroup-internal.h @@ -5,6 +5,7 @@ #include #include #include +#include /* * A cgroup can be associated with multiple css_sets as different tasks may @@ -134,10 +135,13 @@ static inline void put_css_set(struct css_set *cset) * can see it. Similar to atomic_dec_and_lock(), but for an * rwlock */ - if (atomic_add_unless(&cset->refcount, -1, 1)) + spin_lock_irqsave(&css_set_lock, flags); + if (refcount_read(&cset->refcount) != 1) { + WARN_ON(refcount_dec_and_test(&cset->refcount)); + spin_unlock_irqrestore(&css_set_lock, flags); return; + } - spin_lock_irqsave(&css_set_lock, flags); put_css_set_locked(cset); spin_unlock_irqrestore(&css_set_lock, flags); } @@ -147,7 +151,7 @@ static inline void put_css_set(struct css_set *cset) */ static inline void get_css_set(struct css_set *cset) { - atomic_inc(&cset->refcount); + refcount_inc(&cset->refcount); } bool cgroup_ssid_enabled(int ssid); diff --git a/kernel/cgroup/cgroup-v1.c b/kernel/cgroup/cgroup-v1.c index fc34bcf..9269179 100644 --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -343,7 +343,7 @@ static int cgroup_task_count(const struct cgroup *cgrp) spin_lock_irq(&css_set_lock); list_for_each_entry(link, &cgrp->cset_links, cset_link) - count += atomic_read(&link->cset->refcount); + count += refcount_read(&link->cset->refcount); spin_unlock_irq(&css_set_lock); return count; } @@ -1283,7 +1283,7 @@ static u64 current_css_set_refcount_read(struct cgroup_subsys_state *css, u64 count; rcu_read_lock(); - count = atomic_read(&task_css_set(current)->refcount); + count = refcount_read(&task_css_set(current)->refcount); rcu_read_unlock(); return count; } diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index 5b94c79..59aba84 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -553,7 +553,7 @@ EXPORT_SYMBOL_GPL(of_css); * haven't been created. */ struct css_set init_css_set = { - .refcount = ATOMIC_INIT(1), + .refcount = REFCOUNT_INIT(1), .tasks = LIST_HEAD_INIT(init_css_set.tasks), .mg_tasks = LIST_HEAD_INIT(init_css_set.mg_tasks), .task_iters = LIST_HEAD_INIT(init_css_set.task_iters), @@ -723,7 +723,7 @@ void put_css_set_locked(struct css_set *cset) lockdep_assert_held(&css_set_lock); - if (!atomic_dec_and_test(&cset->refcount)) + if (!refcount_dec_and_test(&cset->refcount)) return; /* This css_set is dead. unlink it and release cgroup and css refs */ @@ -976,7 +976,7 @@ static struct css_set *find_css_set(struct css_set *old_cset, return NULL; } - atomic_set(&cset->refcount, 1); + refcount_set(&cset->refcount, 1); INIT_LIST_HEAD(&cset->tasks); INIT_LIST_HEAD(&cset->mg_tasks); INIT_LIST_HEAD(&cset->task_iters); @@ -5064,4 +5064,4 @@ int cgroup_bpf_update(struct cgroup *cgrp, struct bpf_prog *prog, mutex_unlock(&cgroup_mutex); return ret; } -#endif /* CONFIG_CGROUP_BPF */ +#endif /* CONFIG_CGROUP_BPF */ \ No newline at end of file -- 2.7.4