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Commit 8851ab52 authored by Reshetova, Elena's avatar Reshetova, Elena Committed by David S. Miller
Browse files

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: default avatarElena Reshetova <elena.reshetova@intel.com>
Signed-off-by: default avatarHans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarDavid Windsor <dwindsor@gmail.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 41c6d650

include/linux/igmp.h

+2 −1
Original line number Diff line number Diff line
@@ -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;

net/ipv4/igmp.c

+5 −5
Original line number Diff line number Diff line
@@ -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);