[PATCH 5.10 047/105] igmp: Fix data-races around sysctl_igmp_max_msf.

Greg Kroah-Hartman
2022-07-27T16:52:30Z

From: Kuniyuki Iwashima <kuniyu@amazon.com>

[ Upstream commit 6ae0f2e553737b8cce49a1372573c81130ffa80e ]

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

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/ipv4/igmp.c | 2 +-
net/ipv4/ip_sockglue.c | 6 +++---
2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c
index 1a70664dcb1a..428cc3a4c36f 100644
--- a/net/ipv4/igmp.c
+++ b/net/ipv4/igmp.c
@@ -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;
}
diff --git a/net/ipv4/ip_sockglue.c b/net/ipv4/ip_sockglue.c
index ec6036713e2c..22507a6a3f71 100644
--- a/net/ipv4/ip_sockglue.c
+++ b/net/ipv4/ip_sockglue.c
@@ -783,7 +783,7 @@ 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);
@@ -1242,7 +1242,7 @@ 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;
--
2.35.1