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net, l2tp: convert l2tp_tunnel.ref_count from atomic_t to refcount_t

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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>
This commit is contained in:
Reshetova, Elena 2017-07-04 15:52:57 +03:00 committed by David S. Miller
parent 58951dde05
commit fbea9e0760
4 changed files with 12 additions and 11 deletions
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14
net/l2tp/l2tp_core.c
View File

@ -132,12 +132,12 @@ static inline struct l2tp_net *l2tp_pernet(const struct net *net)
*/
static inline void l2tp_tunnel_inc_refcount_1(struct l2tp_tunnel *tunnel)
{
atomic_inc(&tunnel->ref_count);
refcount_inc(&tunnel->ref_count);
}
static inline void l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel *tunnel)
{
if (atomic_dec_and_test(&tunnel->ref_count))
if (refcount_dec_and_test(&tunnel->ref_count))
l2tp_tunnel_free(tunnel);
}
#ifdef L2TP_REFCNT_DEBUG
@ -145,14 +145,14 @@ static inline void l2tp_tunnel_dec_refcount_1(struct l2tp_tunnel *tunnel)
do { \
pr_debug("l2tp_tunnel_inc_refcount: %s:%d %s: cnt=%d\n", \
__func__, __LINE__, (_t)->name, \
atomic_read(&_t->ref_count)); \
refcount_read(&_t->ref_count)); \
l2tp_tunnel_inc_refcount_1(_t); \
} while (0)
#define l2tp_tunnel_dec_refcount(_t) \
do { \
pr_debug("l2tp_tunnel_dec_refcount: %s:%d %s: cnt=%d\n", \
__func__, __LINE__, (_t)->name, \
atomic_read(&_t->ref_count)); \
refcount_read(&_t->ref_count)); \
l2tp_tunnel_dec_refcount_1(_t); \
} while (0)
#else
@ -1353,7 +1353,7 @@ static void l2tp_udp_encap_destroy(struct sock *sk)
*/
static void l2tp_tunnel_free(struct l2tp_tunnel *tunnel)
{
BUG_ON(atomic_read(&tunnel->ref_count) != 0);
BUG_ON(refcount_read(&tunnel->ref_count) != 0);
BUG_ON(tunnel->sock != NULL);
l2tp_info(tunnel, L2TP_MSG_CONTROL, "%s: free...\n", tunnel->name);
kfree_rcu(tunnel, rcu);
@ -1667,7 +1667,7 @@ int l2tp_tunnel_create(struct net *net, int fd, int version, u32 tunnel_id, u32
/* Bump the reference count. The tunnel context is deleted
* only when this drops to zero. Must be done before list insertion
*/
l2tp_tunnel_inc_refcount(tunnel);
refcount_set(&tunnel->ref_count, 1);
spin_lock_bh(&pn->l2tp_tunnel_list_lock);
list_add_rcu(&tunnel->list, &pn->l2tp_tunnel_list);
spin_unlock_bh(&pn->l2tp_tunnel_list_lock);
@ -1706,7 +1706,7 @@ void l2tp_session_free(struct l2tp_session *session)
{
struct l2tp_tunnel *tunnel = session->tunnel;
BUG_ON(atomic_read(&session->ref_count) != 0);
BUG_ON(refcount_read(&session->ref_count) != 0);
if (tunnel) {
BUG_ON(tunnel->magic != L2TP_TUNNEL_MAGIC);

3
net/l2tp/l2tp_core.h
View File

@ -7,6 +7,7 @@
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/refcount.h>
#ifndef _L2TP_CORE_H_
#define _L2TP_CORE_H_
@ -177,7 +178,7 @@ struct l2tp_tunnel {
struct list_head list; /* Keep a list of all tunnels */
struct net *l2tp_net; /* the net we belong to */
atomic_t ref_count;
refcount_t ref_count;
#ifdef CONFIG_DEBUG_FS
void (*show)(struct seq_file *m, void *arg);
#endif

4
net/l2tp/l2tp_debugfs.c
View File

@ -145,7 +145,7 @@ static void l2tp_dfs_seq_tunnel_show(struct seq_file *m, void *v)
"");
seq_printf(m, " %d sessions, refcnt %d/%d\n", session_count,
tunnel->sock ? refcount_read(&tunnel->sock->sk_refcnt) : 0,
atomic_read(&tunnel->ref_count));
refcount_read(&tunnel->ref_count));
seq_printf(m, " %08x rx %ld/%ld/%ld rx %ld/%ld/%ld\n",
tunnel->debug,
atomic_long_read(&tunnel->stats.tx_packets),
@ -170,7 +170,7 @@ static void l2tp_dfs_seq_session_show(struct seq_file *m, void *v)
"");
if (session->send_seq || session->recv_seq)
seq_printf(m, " nr %hu, ns %hu\n", session->nr, session->ns);
seq_printf(m, " refcnt %d\n", atomic_read(&session->ref_count));
seq_printf(m, " refcnt %d\n", refcount_read(&session->ref_count));
seq_printf(m, " config %d/%d/%c/%c/%s/%s %08x %u\n",
session->mtu, session->mru,
session->recv_seq ? 'R' : '-',

2
net/l2tp/l2tp_ppp.c
View File

@ -1616,7 +1616,7 @@ static void pppol2tp_seq_tunnel_show(struct seq_file *m, void *v)
seq_printf(m, "\nTUNNEL '%s', %c %d\n",
tunnel->name,
(tunnel == tunnel->sock->sk_user_data) ? 'Y' : 'N',
atomic_read(&tunnel->ref_count) - 1);
refcount_read(&tunnel->ref_count) - 1);
seq_printf(m, " %08x %ld/%ld/%ld %ld/%ld/%ld\n",
tunnel->debug,
atomic_long_read(&tunnel->stats.tx_packets),