From mboxrd@z Thu Jan 1 00:00:00 1970 From: Elena Reshetova Subject: [PATCH 04/15] kernel: convert task_struct.usage from atomic_t to refcount_t Date: Fri, 7 Jul 2017 12:04:18 +0300 Message-ID: <1499418269-3686-5-git-send-email-elena.reshetova@intel.com> References: <1499418269-3686-1-git-send-email-elena.reshetova@intel.com> Return-path: In-Reply-To: <1499418269-3686-1-git-send-email-elena.reshetova-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org> Sender: cgroups-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-audit-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, linux-fsdevel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, peterz-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org, gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, viro-RmSDqhL/yNMiFSDQTTA3OLVCufUGDwFn@public.gmane.org, tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, mingo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org, lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org, acme-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, alexander.shishkin-VuQAYsv1563Yd54FQh9/CA@public.gmane.org, eparis-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org, arnd-r2nGTMty4D4@public.gmane.org, luto-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, keescook-F7+t8E8rja9g9hUCZPvPmw@public.gmane.org, Elena Reshetova , Hans Liljestrand , David Windsor 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/init_task.h | 2 +- include/linux/sched.h | 3 ++- include/linux/sched/task.h | 4 ++-- kernel/fork.c | 4 ++-- 4 files changed, 7 insertions(+), 6 deletions(-) diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 369211d..348466a 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -228,7 +228,7 @@ extern struct cred init_cred; INIT_TASK_TI(tsk) \ .state = 0, \ .stack = init_stack, \ - .usage = ATOMIC_INIT(2), \ + .usage = REFCOUNT_INIT(2), \ .flags = PF_KTHREAD, \ .prio = MAX_PRIO-20, \ .static_prio = MAX_PRIO-20, \ diff --git a/include/linux/sched.h b/include/linux/sched.h index 4e933f3..6a01517 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -20,6 +20,7 @@ #include #include #include +#include #include #include #include @@ -516,7 +517,7 @@ struct task_struct { randomized_struct_fields_start void *stack; - atomic_t usage; + refcount_t usage; /* Per task flags (PF_*), defined further below: */ unsigned int flags; unsigned int ptrace; diff --git a/include/linux/sched/task.h b/include/linux/sched/task.h index c97e5f0..afd5e58 100644 --- a/include/linux/sched/task.h +++ b/include/linux/sched/task.h @@ -86,13 +86,13 @@ extern void sched_exec(void); #define sched_exec() {} #endif -#define get_task_struct(tsk) do { atomic_inc(&(tsk)->usage); } while(0) +#define get_task_struct(tsk) do { refcount_inc(&(tsk)->usage); } while(0) extern void __put_task_struct(struct task_struct *t); static inline void put_task_struct(struct task_struct *t) { - if (atomic_dec_and_test(&t->usage)) + if (refcount_dec_and_test(&t->usage)) __put_task_struct(t); } diff --git a/kernel/fork.c b/kernel/fork.c index a9763f6..c549b0b 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -406,7 +406,7 @@ static inline void put_signal_struct(struct signal_struct *sig) void __put_task_struct(struct task_struct *tsk) { WARN_ON(!tsk->exit_state); - WARN_ON(atomic_read(&tsk->usage)); + WARN_ON(refcount_read(&tsk->usage)); WARN_ON(tsk == current); cgroup_free(tsk); @@ -561,7 +561,7 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node) * One for us, one for whoever does the "release_task()" (usually * parent) */ - atomic_set(&tsk->usage, 2); + refcount_set(&tsk->usage, 2); #ifdef CONFIG_BLK_DEV_IO_TRACE tsk->btrace_seq = 0; #endif -- 2.7.4