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Commit f74370b8 authored by Elena Reshetova's avatar Elena Reshetova Committed by Linus Torvalds
Browse files

ipc: convert sem_undo_list.refcnt from atomic_t to refcount_t 

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.

Link: http://lkml.kernel.org/r/1499417992-3238-3-git-send-email-elena.reshetova@intel.com


Signed-off-by: default avatarElena Reshetova <elena.reshetova@intel.com>
Signed-off-by: default avatarHans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarDavid Windsor <dwindsor@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Serge Hallyn <serge@hallyn.com>
Cc: <arozansk@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent a2e0602c

ipc/sem.c

+4 −4
Original line number Original line Diff line number Diff line
@@ -122,7 +122,7 @@ struct sem_undo { 
 * that may be shared among all a CLONE_SYSVSEM task group.

 * that may be shared among all a CLONE_SYSVSEM task group.

 */

 */

struct sem_undo_list {

struct sem_undo_list {

	atomic_t		refcnt;

	refcount_t		refcnt;

	spinlock_t		lock;

	spinlock_t		lock;

	struct list_head	list_proc;

	struct list_head	list_proc;

};

};
@@ -1642,7 +1642,7 @@ static inline int get_undo_list(struct sem_undo_list **undo_listp) 
		if (undo_list == NULL)

		if (undo_list == NULL)

			return -ENOMEM;

			return -ENOMEM;

		spin_lock_init(&undo_list->lock);

		spin_lock_init(&undo_list->lock);

		atomic_set(&undo_list->refcnt, 1);

		refcount_set(&undo_list->refcnt, 1);

		INIT_LIST_HEAD(&undo_list->list_proc);

		INIT_LIST_HEAD(&undo_list->list_proc);





		current->sysvsem.undo_list = undo_list;

		current->sysvsem.undo_list = undo_list;
@@ -2041,7 +2041,7 @@ int copy_semundo(unsigned long clone_flags, struct task_struct *tsk) 
		error = get_undo_list(&undo_list);

		error = get_undo_list(&undo_list);

		if (error)

		if (error)

			return error;

			return error;

		atomic_inc(&undo_list->refcnt);

		refcount_inc(&undo_list->refcnt);

		tsk->sysvsem.undo_list = undo_list;

		tsk->sysvsem.undo_list = undo_list;

	} else

	} else

		tsk->sysvsem.undo_list = NULL;

		tsk->sysvsem.undo_list = NULL;
@@ -2070,7 +2070,7 @@ void exit_sem(struct task_struct *tsk) 
		return;

		return;

	tsk->sysvsem.undo_list = NULL;

	tsk->sysvsem.undo_list = NULL;





	if (!atomic_dec_and_test(&ulp->refcnt))

	if (!refcount_dec_and_test(&ulp->refcnt))

		return;

		return;





	for (;;) {

	for (;;) {