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-rw-r--r--kernel/ucount.c10
1 files changed, 7 insertions, 3 deletions
diff --git a/kernel/ucount.c b/kernel/ucount.c
index 87799e2379bd..77be3bbe3cc4 100644
--- a/kernel/ucount.c
+++ b/kernel/ucount.c
@@ -160,6 +160,7 @@ struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid)
{
struct hlist_head *hashent = ucounts_hashentry(ns, uid);
struct ucounts *ucounts, *new;
+ long overflow;
spin_lock_irq(&ucounts_lock);
ucounts = find_ucounts(ns, uid, hashent);
@@ -184,8 +185,12 @@ struct ucounts *alloc_ucounts(struct user_namespace *ns, kuid_t uid)
return new;
}
}
+ overflow = atomic_add_negative(1, &ucounts->count);
spin_unlock_irq(&ucounts_lock);
- ucounts = get_ucounts(ucounts);
+ if (overflow) {
+ put_ucounts(ucounts);
+ return NULL;
+ }
return ucounts;
}
@@ -193,8 +198,7 @@ void put_ucounts(struct ucounts *ucounts)
{
unsigned long flags;
- if (atomic_dec_and_test(&ucounts->count)) {
- spin_lock_irqsave(&ucounts_lock, flags);
+ if (atomic_dec_and_lock_irqsave(&ucounts->count, &ucounts_lock, flags)) {
hlist_del_init(&ucounts->node);
spin_unlock_irqrestore(&ucounts_lock, flags);
kfree(ucounts);