Commit 6ae0f2e5 authored by Kuniyuki Iwashima's avatar Kuniyuki Iwashima Committed by David S. Miller
Browse files

igmp: Fix data-races around sysctl_igmp_max_msf. 



While reading sysctl_igmp_max_msf, it can be changed concurrently.
Thus, we need to add READ_ONCE() to its readers.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: default avatarKuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 6305d821

net/ipv4/igmp.c

+1 −1
Original line number Diff line number Diff line
@@ -2384,7 +2384,7 @@ int ip_mc_source(int add, int omode, struct sock *sk, struct 
	}

	/* else, add a new source to the filter */



	if (psl && psl->sl_count >= net->ipv4.sysctl_igmp_max_msf) {

	if (psl && psl->sl_count >= READ_ONCE(net->ipv4.sysctl_igmp_max_msf)) {

		err = -ENOBUFS;

		goto done;

	}

net/ipv4/ip_sockglue.c

+3 −3
Original line number Diff line number Diff line
@@ -782,7 +782,7 @@ static int ip_set_mcast_msfilter(struct sock *sk, sockptr_t optval, int optlen) 
	/* numsrc >= (4G-140)/128 overflow in 32 bits */

	err = -ENOBUFS;

	if (gsf->gf_numsrc >= 0x1ffffff ||

	    gsf->gf_numsrc > sock_net(sk)->ipv4.sysctl_igmp_max_msf)

	    gsf->gf_numsrc > READ_ONCE(sock_net(sk)->ipv4.sysctl_igmp_max_msf))

		goto out_free_gsf;



	err = -EINVAL;
@@ -832,7 +832,7 @@ static int compat_ip_set_mcast_msfilter(struct sock *sk, sockptr_t optval, 


	/* numsrc >= (4G-140)/128 overflow in 32 bits */

	err = -ENOBUFS;

	if (n > sock_net(sk)->ipv4.sysctl_igmp_max_msf)

	if (n > READ_ONCE(sock_net(sk)->ipv4.sysctl_igmp_max_msf))

		goto out_free_gsf;

	err = set_mcast_msfilter(sk, gf32->gf_interface, n, gf32->gf_fmode,

				 &gf32->gf_group, gf32->gf_slist_flex);
@@ -1244,7 +1244,7 @@ static int do_ip_setsockopt(struct sock *sk, int level, int optname, 
		}

		/* numsrc >= (1G-4) overflow in 32 bits */

		if (msf->imsf_numsrc >= 0x3ffffffcU ||

		    msf->imsf_numsrc > net->ipv4.sysctl_igmp_max_msf) {

		    msf->imsf_numsrc > READ_ONCE(net->ipv4.sysctl_igmp_max_msf)) {

			kfree(msf);

			err = -ENOBUFS;

			break;