net, sctp: convert sctp_auth_bytes.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>

diff --git a/include/net/sctp/auth.h b/include/net/sctp/auth.h
index 171244b..e5c57d0 100644 (file)
--- 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 8ffa598..e001b01 100644 (file)
--- 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;