[PATCH 14/17] net: convert inet_frag_queue.refcnt from atomic_t to refcount_t

From: Elena Reshetova
Date: Thu Mar 16 2017 - 11:30:12 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/inet_frag.h | 4 ++--
net/ipv4/inet_fragment.c | 14 +++++++-------
net/ipv4/ip_fragment.c | 2 +-
3 files changed, 10 insertions(+), 10 deletions(-)

diff --git a/include/net/inet_frag.h b/include/net/inet_frag.h
index 5894730..5a334bf 100644
--- a/include/net/inet_frag.h
+++ b/include/net/inet_frag.h
@@ -50,7 +50,7 @@ struct inet_frag_queue {
spinlock_t lock;
struct timer_list timer;
struct hlist_node list;
- atomic_t refcnt;
+ refcount_t refcnt;
struct sk_buff *fragments;
struct sk_buff *fragments_tail;
ktime_t stamp;
@@ -129,7 +129,7 @@ void inet_frag_maybe_warn_overflow(struct inet_frag_queue *q,

static inline void inet_frag_put(struct inet_frag_queue *q, struct inet_frags *f)
{
- if (atomic_dec_and_test(&q->refcnt))
+ if (refcount_dec_and_test(&q->refcnt))
inet_frag_destroy(q, f);
}

diff --git a/net/ipv4/inet_fragment.c b/net/ipv4/inet_fragment.c
index b5e9317..96e95e8 100644
--- a/net/ipv4/inet_fragment.c
+++ b/net/ipv4/inet_fragment.c
@@ -276,11 +276,11 @@ static inline void fq_unlink(struct inet_frag_queue *fq, struct inet_frags *f)
void inet_frag_kill(struct inet_frag_queue *fq, struct inet_frags *f)
{
if (del_timer(&fq->timer))
- atomic_dec(&fq->refcnt);
+ refcount_dec(&fq->refcnt);

if (!(fq->flags & INET_FRAG_COMPLETE)) {
fq_unlink(fq, f);
- atomic_dec(&fq->refcnt);
+ refcount_dec(&fq->refcnt);
}
}
EXPORT_SYMBOL(inet_frag_kill);
@@ -329,7 +329,7 @@ static struct inet_frag_queue *inet_frag_intern(struct netns_frags *nf,
*/
hlist_for_each_entry(qp, &hb->chain, list) {
if (qp->net == nf && f->match(qp, arg)) {
- atomic_inc(&qp->refcnt);
+ refcount_inc(&qp->refcnt);
spin_unlock(&hb->chain_lock);
qp_in->flags |= INET_FRAG_COMPLETE;
inet_frag_put(qp_in, f);
@@ -339,9 +339,9 @@ static struct inet_frag_queue *inet_frag_intern(struct netns_frags *nf,
#endif
qp = qp_in;
if (!mod_timer(&qp->timer, jiffies + nf->timeout))
- atomic_inc(&qp->refcnt);
+ refcount_inc(&qp->refcnt);

- atomic_inc(&qp->refcnt);
+ refcount_inc(&qp->refcnt);
hlist_add_head(&qp->list, &hb->chain);

spin_unlock(&hb->chain_lock);
@@ -370,7 +370,7 @@ static struct inet_frag_queue *inet_frag_alloc(struct netns_frags *nf,

setup_timer(&q->timer, f->frag_expire, (unsigned long)q);
spin_lock_init(&q->lock);
- atomic_set(&q->refcnt, 1);
+ refcount_set(&q->refcnt, 1);

return q;
}
@@ -405,7 +405,7 @@ struct inet_frag_queue *inet_frag_find(struct netns_frags *nf,
spin_lock(&hb->chain_lock);
hlist_for_each_entry(q, &hb->chain, list) {
if (q->net == nf && f->match(q, key)) {
- atomic_inc(&q->refcnt);
+ refcount_inc(&q->refcnt);
spin_unlock(&hb->chain_lock);
return q;
}
diff --git a/net/ipv4/ip_fragment.c b/net/ipv4/ip_fragment.c
index bbe7f72..4fed6f6 100644
--- a/net/ipv4/ip_fragment.c
+++ b/net/ipv4/ip_fragment.c
@@ -303,7 +303,7 @@ static int ip_frag_reinit(struct ipq *qp)
unsigned int sum_truesize = 0;

if (!mod_timer(&qp->q.timer, jiffies + qp->q.net->timeout)) {
- atomic_inc(&qp->q.refcnt);
+ refcount_inc(&qp->q.refcnt);
return -ETIMEDOUT;
}

--
2.7.4