netdev - [PATCH 15/23] net, xfrm: convert sec_path.refcnt from atomic_t to refcount

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Date:   Fri, 17 Mar 2017 14:10:38 +0200
From:   Elena Reshetova <elena.reshetova@...el.com>
To:     netdev@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, linux-rdma@...r.kernel.org,
        davem@...emloft.net, linux-x25@...r.kernel.org,
        linux-sctp@...r.kernel.org, vyasevich@...il.com,
        nhorman@...driver.com, linux-hams@...r.kernel.org,
        linux-nfs@...r.kernel.org, ceph-devel@...r.kernel.org,
        zyan@...hat.com, sage@...hat.com, bfields@...ldses.org,
        jlayton@...chiereds.net, steffen.klassert@...unet.com,
        herbert@...dor.apana.org.au, santosh.shilimkar@...cle.com,
        jreuter@...na.de, ralf@...ux-mips.org, peterz@...radead.org,
        keescook@...omium.org, Elena Reshetova <elena.reshetova@...el.com>,
        Hans Liljestrand <ishkamiel@...il.com>,
        David Windsor <dwindsor@...il.com>
Subject: [PATCH 15/23] net, xfrm: convert sec_path.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@...el.com>
Signed-off-by: Hans Liljestrand <ishkamiel@...il.com>
Signed-off-by: Kees Cook <keescook@...omium.org>
Signed-off-by: David Windsor <dwindsor@...il.com>
---
 include/net/xfrm.h    | 6 +++---
 net/xfrm/xfrm_input.c | 4 ++--
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index be30846..35d1cca 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1005,7 +1005,7 @@ struct xfrm_offload {
 };
 
 struct sec_path {
-	atomic_t		refcnt;
+	refcount_t		refcnt;
 	int			len;
 	int			olen;
 
@@ -1026,7 +1026,7 @@ static inline struct sec_path *
 secpath_get(struct sec_path *sp)
 {
 	if (sp)
-		atomic_inc(&sp->refcnt);
+		refcount_inc(&sp->refcnt);
 	return sp;
 }
 
@@ -1035,7 +1035,7 @@ void __secpath_destroy(struct sec_path *sp);
 static inline void
 secpath_put(struct sec_path *sp)
 {
-	if (sp && atomic_dec_and_test(&sp->refcnt))
+	if (sp && refcount_dec_and_test(&sp->refcnt))
 		__secpath_destroy(sp);
 }
 
diff --git a/net/xfrm/xfrm_input.c b/net/xfrm/xfrm_input.c
index 46bdb4f..203ba90 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -114,7 +114,7 @@ struct sec_path *secpath_dup(struct sec_path *src)
 		for (i = 0; i < sp->len; i++)
 			xfrm_state_hold(sp->xvec[i]);
 	}
-	atomic_set(&sp->refcnt, 1);
+	refcount_set(&sp->refcnt, 1);
 	return sp;
 }
 EXPORT_SYMBOL(secpath_dup);
@@ -124,7 +124,7 @@ int secpath_set(struct sk_buff *skb)
 	struct sec_path *sp;
 
 	/* Allocate new secpath or COW existing one. */
-	if (!skb->sp || atomic_read(&skb->sp->refcnt) != 1) {
+	if (!skb->sp || refcount_read(&skb->sp->refcnt) != 1) {
 		sp = secpath_dup(skb->sp);
 		if (!sp)
 			return -ENOMEM;
-- 
2.7.4