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Commit fb5c2c17 authored by Reshetova, Elena's avatar Reshetova, Elena Committed by David S. Miller
Browse files

net: convert packet_fanout.sk_ref 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 b4217b82

net/packet/af_packet.c

+4 −4
Original line number Diff line number Diff line
@@ -1739,7 +1739,7 @@ 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;
@@ -1753,10 +1753,10 @@ 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;

		}
@@ -1785,7 +1785,7 @@ 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;

net/packet/internal.h

+3 −1
Original line number Diff line number Diff line 
#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;

};