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authorFlorian Westphal <fw@strlen.de>2022-05-20 01:02:03 +0300
committerPablo Neira Ayuso <pablo@netfilter.org>2022-05-27 12:16:33 +0300
commitffd219efd9ee1ceccc7ccfa9361fd40705680fc3 (patch)
tree24deb559efab08e0288c735ac82d50435b6e69ca /net
parent02ded5a173619b11728b8bf75a3fd995a2c1ff28 (diff)
downloadlinux-ffd219efd9ee1ceccc7ccfa9361fd40705680fc3.tar.xz
netfilter: nfnetlink: fix warn in nfnetlink_unbind
syzbot reports following warn: WARNING: CPU: 0 PID: 3600 at net/netfilter/nfnetlink.c:703 nfnetlink_unbind+0x357/0x3b0 net/netfilter/nfnetlink.c:694 The syzbot generated program does this: socket(AF_NETLINK, SOCK_RAW, NETLINK_NETFILTER) = 3 setsockopt(3, SOL_NETLINK, NETLINK_DROP_MEMBERSHIP, [1], 4) = 0 ... which triggers 'WARN_ON_ONCE(nfnlnet->ctnetlink_listeners == 0)' check. Instead of counting, just enable reporting for every bind request and check if we still have listeners on unbind. While at it, also add the needed bounds check on nfnl_group2type[] access. Reported-by: <syzbot+4903218f7fba0a2d6226@syzkaller.appspotmail.com> Reported-by: <syzbot+afd2d80e495f96049571@syzkaller.appspotmail.com> Fixes: 2794cdb0b97b ("netfilter: nfnetlink: allow to detect if ctnetlink listeners exist") Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Diffstat (limited to 'net')
-rw-r--r--net/netfilter/nfnetlink.c24
1 files changed, 5 insertions, 19 deletions
diff --git a/net/netfilter/nfnetlink.c b/net/netfilter/nfnetlink.c
index ad3bbe34ca88..2f7c477fc9e7 100644
--- a/net/netfilter/nfnetlink.c
+++ b/net/netfilter/nfnetlink.c
@@ -45,7 +45,6 @@ MODULE_DESCRIPTION("Netfilter messages via netlink socket");
static unsigned int nfnetlink_pernet_id __read_mostly;
struct nfnl_net {
- unsigned int ctnetlink_listeners;
struct sock *nfnl;
};
@@ -673,18 +672,8 @@ static int nfnetlink_bind(struct net *net, int group)
#ifdef CONFIG_NF_CONNTRACK_EVENTS
if (type == NFNL_SUBSYS_CTNETLINK) {
- struct nfnl_net *nfnlnet = nfnl_pernet(net);
-
nfnl_lock(NFNL_SUBSYS_CTNETLINK);
-
- if (WARN_ON_ONCE(nfnlnet->ctnetlink_listeners == UINT_MAX)) {
- nfnl_unlock(NFNL_SUBSYS_CTNETLINK);
- return -EOVERFLOW;
- }
-
- nfnlnet->ctnetlink_listeners++;
- if (nfnlnet->ctnetlink_listeners == 1)
- WRITE_ONCE(net->ct.ctnetlink_has_listener, true);
+ WRITE_ONCE(net->ct.ctnetlink_has_listener, true);
nfnl_unlock(NFNL_SUBSYS_CTNETLINK);
}
#endif
@@ -694,15 +683,12 @@ static int nfnetlink_bind(struct net *net, int group)
static void nfnetlink_unbind(struct net *net, int group)
{
#ifdef CONFIG_NF_CONNTRACK_EVENTS
- int type = nfnl_group2type[group];
-
- if (type == NFNL_SUBSYS_CTNETLINK) {
- struct nfnl_net *nfnlnet = nfnl_pernet(net);
+ if (group <= NFNLGRP_NONE || group > NFNLGRP_MAX)
+ return;
+ if (nfnl_group2type[group] == NFNL_SUBSYS_CTNETLINK) {
nfnl_lock(NFNL_SUBSYS_CTNETLINK);
- WARN_ON_ONCE(nfnlnet->ctnetlink_listeners == 0);
- nfnlnet->ctnetlink_listeners--;
- if (nfnlnet->ctnetlink_listeners == 0)
+ if (!nfnetlink_has_listeners(net, group))
WRITE_ONCE(net->ct.ctnetlink_has_listener, false);
nfnl_unlock(NFNL_SUBSYS_CTNETLINK);
}