[PATCH 28/36] net, xfrm: convert sec_path.refcnt from atomic_t to refcount_t

From: Elena Reshetova
Date: Tue Jul 04 2017 - 08:58:10 EST


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@xxxxxxxxx>
Signed-off-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: David Windsor <dwindsor@xxxxxxxxx>
---
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 e1bd1de..c0916ab 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -1030,7 +1030,7 @@ struct xfrm_offload {
};

struct sec_path {
- atomic_t refcnt;
+ refcount_t refcnt;
int len;
int olen;

@@ -1051,7 +1051,7 @@ static inline struct sec_path *
secpath_get(struct sec_path *sp)
{
if (sp)
- atomic_inc(&sp->refcnt);
+ refcount_inc(&sp->refcnt);
return sp;
}

@@ -1060,7 +1060,7 @@ 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 9de4b1d..923205e 100644
--- a/net/xfrm/xfrm_input.c
+++ b/net/xfrm/xfrm_input.c
@@ -116,7 +116,7 @@ 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);
@@ -126,7 +126,7 @@ 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