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ipc: convert sem_undo_list.refcnt from atomic_t to refcount_t

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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: Elena Reshetova <elena.reshetova@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Elena Reshetova 2017-09-08 16:17:42 -07:00 committed by Linus Torvalds
parent a2e0602c36
commit f74370b86e
1 changed files with 4 additions and 4 deletions
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8
ipc/sem.c
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@ -122,7 +122,7 @@ struct sem_undo {
* that may be shared among all a CLONE_SYSVSEM task group.
*/
struct sem_undo_list {
atomic_t refcnt;
refcount_t refcnt;
spinlock_t lock;
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)
return -ENOMEM;
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);
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);
if (error)
return error;
atomic_inc(&undo_list->refcnt);
refcount_inc(&undo_list->refcnt);
tsk->sysvsem.undo_list = undo_list;
} else
tsk->sysvsem.undo_list = NULL;
@ -2070,7 +2070,7 @@ void exit_sem(struct task_struct *tsk)
return;
tsk->sysvsem.undo_list = NULL;
if (!atomic_dec_and_test(&ulp->refcnt))
if (!refcount_dec_and_test(&ulp->refcnt))
return;
for (;;) {