From 87e9f0315952b0dd8b5e51ba04beda03efc009d9 Mon Sep 17 00:00:00 2001 From: WANG Cong Date: Tue, 3 Nov 2015 15:41:16 -0800 Subject: ipv4: fix a potential deadlock in mcast getsockopt() path Sasha reported the following lockdep warning: Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(sk_lock-AF_INET); lock(rtnl_mutex); lock(sk_lock-AF_INET); lock(rtnl_mutex); This is due to that for IP_MSFILTER and MCAST_MSFILTER, we take rtnl lock before the socket lock in setsockopt() path, but take the socket lock before rtnl lock in getsockopt() path. All the rest optnames are setsockopt()-only. Fix this by aligning the getsockopt() path with the setsockopt() path, so that all mcast socket path would be locked in the same order. Note, IPv6 part is different where rtnl lock is not held. Fixes: 54ff9ef36bdf ("ipv4, ipv6: kill ip_mc_{join, leave}_group and ipv6_sock_mc_{join, drop}") Reported-by: Sasha Levin Cc: Marcelo Ricardo Leitner Signed-off-by: Cong Wang Reviewed-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller --- net/ipv4/igmp.c | 12 ++++-------- 1 file changed, 4 insertions(+), 8 deletions(-) (limited to 'net/ipv4/igmp.c') diff --git a/net/ipv4/igmp.c b/net/ipv4/igmp.c index 64aaf3522a59..6baf36e11808 100644 --- a/net/ipv4/igmp.c +++ b/net/ipv4/igmp.c @@ -2392,11 +2392,11 @@ int ip_mc_msfget(struct sock *sk, struct ip_msfilter *msf, struct ip_sf_socklist *psl; struct net *net = sock_net(sk); + ASSERT_RTNL(); + if (!ipv4_is_multicast(addr)) return -EINVAL; - rtnl_lock(); - imr.imr_multiaddr.s_addr = msf->imsf_multiaddr; imr.imr_address.s_addr = msf->imsf_interface; imr.imr_ifindex = 0; @@ -2417,7 +2417,6 @@ int ip_mc_msfget(struct sock *sk, struct ip_msfilter *msf, goto done; msf->imsf_fmode = pmc->sfmode; psl = rtnl_dereference(pmc->sflist); - rtnl_unlock(); if (!psl) { len = 0; count = 0; @@ -2436,7 +2435,6 @@ int ip_mc_msfget(struct sock *sk, struct ip_msfilter *msf, return -EFAULT; return 0; done: - rtnl_unlock(); return err; } @@ -2450,6 +2448,8 @@ int ip_mc_gsfget(struct sock *sk, struct group_filter *gsf, struct inet_sock *inet = inet_sk(sk); struct ip_sf_socklist *psl; + ASSERT_RTNL(); + psin = (struct sockaddr_in *)&gsf->gf_group; if (psin->sin_family != AF_INET) return -EINVAL; @@ -2457,8 +2457,6 @@ int ip_mc_gsfget(struct sock *sk, struct group_filter *gsf, if (!ipv4_is_multicast(addr)) return -EINVAL; - rtnl_lock(); - err = -EADDRNOTAVAIL; for_each_pmc_rtnl(inet, pmc) { @@ -2470,7 +2468,6 @@ int ip_mc_gsfget(struct sock *sk, struct group_filter *gsf, goto done; gsf->gf_fmode = pmc->sfmode; psl = rtnl_dereference(pmc->sflist); - rtnl_unlock(); count = psl ? psl->sl_count : 0; copycount = count < gsf->gf_numsrc ? count : gsf->gf_numsrc; gsf->gf_numsrc = count; @@ -2490,7 +2487,6 @@ int ip_mc_gsfget(struct sock *sk, struct group_filter *gsf, } return 0; done: - rtnl_unlock(); return err; } -- cgit v1.2.3-59-g8ed1b