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.reshet...@intel.com>
Signed-off-by: Hans Liljestrand <ishkam...@gmail.com>
Signed-off-by: Kees Cook <keesc...@chromium.org>
Signed-off-by: David Windsor <dwind...@gmail.com>
---
 include/net/sctp/auth.h | 5 +++--
 net/sctp/auth.c         | 4 ++--
 2 files changed, 5 insertions(+), 4 deletions(-)

diff --git a/include/net/sctp/auth.h b/include/net/sctp/auth.h
index 9b9fb12..328fccc 100644
--- a/include/net/sctp/auth.h
+++ b/include/net/sctp/auth.h
@@ -31,6 +31,7 @@
 #define __sctp_auth_h__
 
 #include <linux/list.h>
+#include <linux/refcount.h>
 
 struct sctp_endpoint;
 struct sctp_association;
@@ -53,7 +54,7 @@ struct sctp_hmac {
  * over SCTP-AUTH
  */
 struct sctp_auth_bytes {
-       atomic_t refcnt;
+       refcount_t refcnt;
        __u32 len;
        __u8  data[];
 };
@@ -76,7 +77,7 @@ static inline void sctp_auth_key_hold(struct sctp_auth_bytes 
*key)
        if (!key)
                return;
 
-       atomic_inc(&key->refcnt);
+       refcount_inc(&key->refcnt);
 }
 
 void sctp_auth_key_put(struct sctp_auth_bytes *key);
diff --git a/net/sctp/auth.c b/net/sctp/auth.c
index f99d485..b6c98fe 100644
--- a/net/sctp/auth.c
+++ b/net/sctp/auth.c
@@ -63,7 +63,7 @@ void sctp_auth_key_put(struct sctp_auth_bytes *key)
        if (!key)
                return;
 
-       if (atomic_dec_and_test(&key->refcnt)) {
+       if (refcount_dec_and_test(&key->refcnt)) {
                kzfree(key);
                SCTP_DBG_OBJCNT_DEC(keys);
        }
@@ -84,7 +84,7 @@ static struct sctp_auth_bytes *sctp_auth_create_key(__u32 
key_len, gfp_t gfp)
                return NULL;
 
        key->len = key_len;
-       atomic_set(&key->refcnt, 1);
+       refcount_set(&key->refcnt, 1);
        SCTP_DBG_OBJCNT_INC(keys);
 
        return key;
-- 
2.7.4

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