net: convert ip_mc_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.

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>

1 files changed, 2 insertions, 1 deletions

diff --git a/include/linux/igmp.h b/include/linux/igmp.h
index 12f6fba6d21a..97caf1821de8 100644
--- a/include/linux/igmp.h
+++ b/include/linux/igmp.h
@@ -18,6 +18,7 @@
 #include <linux/skbuff.h>
 #include <linux/timer.h>
 #include <linux/in.h>
+#include <linux/refcount.h>
 #include <uapi/linux/igmp.h>
 
 static inline struct igmphdr *igmp_hdr(const struct sk_buff *skb)
@@ -84,7 +85,7 @@ struct ip_mc_list {
         struct ip_mc_list __rcu *next_hash;
         struct timer_list       timer;
         int                     users;
-        atomic_t                refcnt;
+        refcount_t              refcnt;
         spinlock_t              lock;
         char                    tm_running;
         char                    reporter;