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net: convert ip_mc_list.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@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 2017-06-30 13:08:02 +03:00 committed by David S. Miller
parent 41c6d650f6
commit 8851ab5267
2 changed files with 7 additions and 6 deletions
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3
include/linux/igmp.h
View File

@ -18,6 +18,7 @@
#include <linux/skbuff.h>
#include <linux/timer.h>
#include <linux/in.h>
#include <linux/refcount.h>
#include <uapi/linux/igmp.h>
static inline struct igmphdr *igmp_hdr(const struct sk_buff *skb)
@ -84,7 +85,7 @@ struct ip_mc_list {
struct ip_mc_list __rcu *next_hash;
struct timer_list timer;
int users;
atomic_t refcnt;
refcount_t refcnt;
spinlock_t lock;
char tm_running;
char reporter;

10
net/ipv4/igmp.c
View File

@ -173,7 +173,7 @@ static int ip_mc_add_src(struct in_device *in_dev, __be32 *pmca, int sfmode,
static void ip_ma_put(struct ip_mc_list *im)
{
if (atomic_dec_and_test(&im->refcnt)) {
if (refcount_dec_and_test(&im->refcnt)) {
in_dev_put(im->interface);
kfree_rcu(im, rcu);
}
@ -199,7 +199,7 @@ static void igmp_stop_timer(struct ip_mc_list *im)
{
spin_lock_bh(&im->lock);
if (del_timer(&im->timer))
atomic_dec(&im->refcnt);
refcount_dec(&im->refcnt);
im->tm_running = 0;
im->reporter = 0;
im->unsolicit_count = 0;
@ -213,7 +213,7 @@ static void igmp_start_timer(struct ip_mc_list *im, int max_delay)
im->tm_running = 1;
if (!mod_timer(&im->timer, jiffies+tv+2))
atomic_inc(&im->refcnt);
refcount_inc(&im->refcnt);
}
static void igmp_gq_start_timer(struct in_device *in_dev)
@ -249,7 +249,7 @@ static void igmp_mod_timer(struct ip_mc_list *im, int max_delay)
spin_unlock_bh(&im->lock);
return;
}
atomic_dec(&im->refcnt);
refcount_dec(&im->refcnt);
}
igmp_start_timer(im, max_delay);
spin_unlock_bh(&im->lock);
@ -1374,7 +1374,7 @@ void ip_mc_inc_group(struct in_device *in_dev, __be32 addr)
/* initial mode is (EX, empty) */
im->sfmode = MCAST_EXCLUDE;
im->sfcount[MCAST_EXCLUDE] = 1;
atomic_set(&im->refcnt, 1);
refcount_set(&im->refcnt, 1);
spin_lock_init(&im->lock);
#ifdef CONFIG_IP_MULTICAST
setup_timer(&im->timer, igmp_timer_expire, (unsigned long)im);