From: Elena Reshetova <elena.reshetova@intel.com> To: mingo@redhat.com Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, peterz@infradead.org, gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk, tj@kernel.org, hannes@cmpxchg.org, lizefan@huawei.com, acme@kernel.org, alexander.shishkin@linux.intel.com, eparis@redhat.com, akpm@linux-foundation.org, arnd@arndb.de, luto@kernel.org, keescook@chromium.org, tglx@linutronix.de, dvhart@infradead.org, ebiederm@xmission.com, linux-mm@kvack.org, axboe@kernel.dk, Elena Reshetova <elena.reshetova@intel.com> Subject: [PATCH 02/15] sched: convert signal_struct.sigcnt to refcount_t Date: Fri, 20 Oct 2017 15:15:44 +0300 [thread overview] Message-ID: <1508501757-15784-3-git-send-email-elena.reshetova@intel.com> (raw) In-Reply-To: <1508501757-15784-1-git-send-email-elena.reshetova@intel.com> atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable signal_struct.sigcnt is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> --- include/linux/sched/signal.h | 2 +- kernel/fork.c | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index b40fbf7..856d957 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -77,7 +77,7 @@ struct thread_group_cputimer { * the locking of signal_struct. */ struct signal_struct { - atomic_t sigcnt; + refcount_t sigcnt; atomic_t live; int nr_threads; struct list_head thread_head; diff --git a/kernel/fork.c b/kernel/fork.c index ab4ddc9..869850b 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -642,7 +642,7 @@ static inline void free_signal_struct(struct signal_struct *sig) static inline void put_signal_struct(struct signal_struct *sig) { - if (atomic_dec_and_test(&sig->sigcnt)) + if (refcount_dec_and_test(&sig->sigcnt)) free_signal_struct(sig); } @@ -1443,7 +1443,7 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) sig->nr_threads = 1; atomic_set(&sig->live, 1); - atomic_set(&sig->sigcnt, 1); + refcount_set(&sig->sigcnt, 1); /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */ sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node); @@ -1950,7 +1950,7 @@ static __latent_entropy struct task_struct *copy_process( } else { current->signal->nr_threads++; atomic_inc(¤t->signal->live); - atomic_inc(¤t->signal->sigcnt); + refcount_inc(¤t->signal->sigcnt); list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group); list_add_tail_rcu(&p->thread_node, -- 2.7.4
WARNING: multiple messages have this Message-ID (diff)
From: Elena Reshetova <elena.reshetova@intel.com> To: mingo@redhat.com Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, peterz@infradead.org, gregkh@linuxfoundation.org, viro@zeniv.linux.org.uk, tj@kernel.org, hannes@cmpxchg.org, lizefan@huawei.com, acme@kernel.org, alexander.shishkin@linux.intel.com, eparis@redhat.com, akpm@linux-foundation.org, arnd@arndb.de, luto@kernel.org, keescook@chromium.org, tglx@linutronix.de, dvhart@infradead.org, ebiederm@xmission.com, linux-mm@kvack.org, axboe@kernel.dk, Elena Reshetova <elena.reshetova@intel.com> Subject: [PATCH 02/15] sched: convert signal_struct.sigcnt to refcount_t Date: Fri, 20 Oct 2017 15:15:44 +0300 [thread overview] Message-ID: <1508501757-15784-3-git-send-email-elena.reshetova@intel.com> (raw) In-Reply-To: <1508501757-15784-1-git-send-email-elena.reshetova@intel.com> atomic_t variables are currently used to implement reference counters with the following properties: - counter is initialized to 1 using atomic_set() - a resource is freed upon counter reaching zero - once counter reaches zero, its further increments aren't allowed - counter schema uses basic atomic operations (set, inc, inc_not_zero, dec_and_test, etc.) Such atomic variables should be converted to a newly provided refcount_t type and API that prevents accidental counter overflows and underflows. This is important since overflows and underflows can lead to use-after-free situation and be exploitable. The variable signal_struct.sigcnt is used as pure reference counter. Convert it to refcount_t and fix up the operations. Suggested-by: Kees Cook <keescook@chromium.org> Reviewed-by: David Windsor <dwindsor@gmail.com> Reviewed-by: Hans Liljestrand <ishkamiel@gmail.com> Signed-off-by: Elena Reshetova <elena.reshetova@intel.com> --- include/linux/sched/signal.h | 2 +- kernel/fork.c | 6 +++--- 2 files changed, 4 insertions(+), 4 deletions(-) diff --git a/include/linux/sched/signal.h b/include/linux/sched/signal.h index b40fbf7..856d957 100644 --- a/include/linux/sched/signal.h +++ b/include/linux/sched/signal.h @@ -77,7 +77,7 @@ struct thread_group_cputimer { * the locking of signal_struct. */ struct signal_struct { - atomic_t sigcnt; + refcount_t sigcnt; atomic_t live; int nr_threads; struct list_head thread_head; diff --git a/kernel/fork.c b/kernel/fork.c index ab4ddc9..869850b 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -642,7 +642,7 @@ static inline void free_signal_struct(struct signal_struct *sig) static inline void put_signal_struct(struct signal_struct *sig) { - if (atomic_dec_and_test(&sig->sigcnt)) + if (refcount_dec_and_test(&sig->sigcnt)) free_signal_struct(sig); } @@ -1443,7 +1443,7 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) sig->nr_threads = 1; atomic_set(&sig->live, 1); - atomic_set(&sig->sigcnt, 1); + refcount_set(&sig->sigcnt, 1); /* list_add(thread_node, thread_head) without INIT_LIST_HEAD() */ sig->thread_head = (struct list_head)LIST_HEAD_INIT(tsk->thread_node); @@ -1950,7 +1950,7 @@ static __latent_entropy struct task_struct *copy_process( } else { current->signal->nr_threads++; atomic_inc(¤t->signal->live); - atomic_inc(¤t->signal->sigcnt); + refcount_inc(¤t->signal->sigcnt); list_add_tail_rcu(&p->thread_group, &p->group_leader->thread_group); list_add_tail_rcu(&p->thread_node, -- 2.7.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>
next prev parent reply other threads:[~2017-10-20 12:16 UTC|newest] Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-10-20 12:15 [PATCH 00/15] v5 kernel core pieces refcount conversions Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova 2017-10-20 12:15 ` [PATCH 01/15] sched: convert sighand_struct.count to refcount_t Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova 2017-10-20 12:43 ` Thomas Gleixner 2017-10-20 12:43 ` Thomas Gleixner 2017-10-23 10:22 ` Reshetova, Elena 2017-10-23 10:22 ` Reshetova, Elena 2017-10-23 10:26 ` Thomas Gleixner 2017-10-23 10:26 ` Thomas Gleixner 2017-10-23 10:26 ` Thomas Gleixner 2017-10-23 10:45 ` Reshetova, Elena 2017-10-23 10:45 ` Reshetova, Elena 2017-10-20 12:15 ` Elena Reshetova [this message] 2017-10-20 12:15 ` [PATCH 02/15] sched: convert signal_struct.sigcnt " Elena Reshetova 2017-10-20 12:15 ` [PATCH 03/15] sched: convert user_struct.__count " Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova 2017-10-20 12:15 ` [PATCH 04/15] sched: convert numa_group.refcount " Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova 2017-10-20 12:15 ` [PATCH 05/15] sched/task_struct: convert task_struct.usage " Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova 2017-10-20 12:15 ` [PATCH 06/15] sched/task_struct: convert task_struct.stack_refcount " Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova 2017-10-20 12:15 ` [PATCH 07/15] perf: convert perf_event_context.refcount " Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova 2017-10-20 12:15 ` [PATCH 08/15] perf/ring_buffer: convert ring_buffer.refcount " Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova 2017-10-20 12:15 ` [PATCH 09/15] perf/ring_buffer: convert ring_buffer.aux_refcount " Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova 2017-10-20 12:15 ` [PATCH 10/15] uprobes: convert uprobe.ref " Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova 2017-10-20 12:15 ` [PATCH 11/15] nsproxy: convert nsproxy.count " Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova 2017-10-20 12:15 ` [PATCH 12/15] groups: convert group_info.usage " Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova 2017-10-20 12:15 ` [PATCH 13/15] creds: convert cred.usage " Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova 2017-10-20 12:15 ` [PATCH 14/15] kcov: convert kcov.refcount " Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova 2017-10-20 12:15 ` [PATCH 15/15] bdi: convert bdi_writeback_congested.refcnt from atomic_t " Elena Reshetova 2017-10-20 12:15 ` Elena Reshetova -- strict thread matches above, loose matches on Subject: below -- 2017-08-30 12:22 [PATCH 00/15] v5 kernel core pieces refcount conversions Elena Reshetova 2017-08-30 12:22 ` [PATCH 02/15] sched: convert signal_struct.sigcnt to refcount_t Elena Reshetova 2017-08-25 9:41 [PATCH 00/15] v4 kernel core pieces refcount conversions Elena Reshetova 2017-08-25 9:41 ` [PATCH 02/15] sched: convert signal_struct.sigcnt to refcount_t Elena Reshetova 2017-07-18 10:29 [PATCH 00/15] v4 kernel core pieces refcount conversions Elena Reshetova 2017-07-18 10:29 ` [PATCH 02/15] sched: convert signal_struct.sigcnt to refcount_t Elena Reshetova
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