net: convert sk_buff.users 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.
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>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 005793e..90cbd86 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -761,7 +761,7 @@ struct sk_buff {
unsigned char *head,
*data;
unsigned int truesize;
- atomic_t users;
+ refcount_t users;
};
#ifdef __KERNEL__
@@ -872,9 +872,9 @@ static inline bool skb_unref(struct sk_buff *skb)
{
if (unlikely(!skb))
return false;
- if (likely(atomic_read(&skb->users) == 1))
+ if (likely(refcount_read(&skb->users) == 1))
smp_rmb();
- else if (likely(!atomic_dec_and_test(&skb->users)))
+ else if (likely(!refcount_dec_and_test(&skb->users)))
return false;
return true;
@@ -1283,7 +1283,7 @@ static inline struct sk_buff *skb_queue_prev(const struct sk_buff_head *list,
*/
static inline struct sk_buff *skb_get(struct sk_buff *skb)
{
- atomic_inc(&skb->users);
+ refcount_inc(&skb->users);
return skb;
}
@@ -1384,7 +1384,7 @@ static inline void __skb_header_release(struct sk_buff *skb)
*/
static inline int skb_shared(const struct sk_buff *skb)
{
- return atomic_read(&skb->users) != 1;
+ return refcount_read(&skb->users) != 1;
}
/**