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>
---
net/packet/af_packet.c | 8 ++++----
net/packet/internal.h | 4 +++-
2 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index ad5e5dc..ef868a7 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -1698,7 +1698,7 @@ static int fanout_add(struct sock *sk, u16 id, u16
type_flags)
match->flags = flags;
INIT_LIST_HEAD(&match->list);
spin_lock_init(&match->lock);
- atomic_set(&match->sk_ref, 0);
+ refcount_set(&match->sk_ref, 0);
fanout_init_data(match);
match->prot_hook.type = po->prot_hook.type;
match->prot_hook.dev = po->prot_hook.dev;
@@ -1712,10 +1712,10 @@ static int fanout_add(struct sock *sk, u16 id, u16
type_flags)
match->prot_hook.type == po->prot_hook.type &&
match->prot_hook.dev == po->prot_hook.dev) {
err = -ENOSPC;
- if (atomic_read(&match->sk_ref) < PACKET_FANOUT_MAX) {
+ if (refcount_read(&match->sk_ref) < PACKET_FANOUT_MAX) {
__dev_remove_pack(&po->prot_hook);
po->fanout = match;
- atomic_inc(&match->sk_ref);
+ refcount_set(&match->sk_ref,
refcount_read(&match->sk_ref) + 1);
__fanout_link(sk, po);
err = 0;
}
@@ -1744,7 +1744,7 @@ static struct packet_fanout *fanout_release(struct sock
*sk)
if (f) {
po->fanout = NULL;
- if (atomic_dec_and_test(&f->sk_ref))
+ if (refcount_dec_and_test(&f->sk_ref))
list_del(&f->list);
else
f = NULL;
diff --git a/net/packet/internal.h b/net/packet/internal.h
index 9ee4631..94d1d40 100644
--- a/net/packet/internal.h
+++ b/net/packet/internal.h
@@ -1,6 +1,8 @@
#ifndef __PACKET_INTERNAL_H__
#define __PACKET_INTERNAL_H__
+#include <linux/refcount.h>
+
struct packet_mclist {
struct packet_mclist *next;
int ifindex;
@@ -86,7 +88,7 @@ struct packet_fanout {
struct list_head list;
struct sock *arr[PACKET_FANOUT_MAX];
spinlock_t lock;
- atomic_t sk_ref;
+ refcount_t sk_ref;
struct packet_type prot_hook ____cacheline_aligned_in_smp;
};
--
2.7.4
