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Subject[PATCH 4.19 042/101] netfilter: nfnetlink_cttimeout: pass default timeout policy to obj_to_nlattr
Date
commit 8866df9264a34e675b4ee8a151db819b87cce2d3 upstream

Otherwise, we hit a NULL pointer deference since handlers always assume
default timeout policy is passed.

netlink: 24 bytes leftover after parsing attributes in process `syz-executor2'.
kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
CPU: 0 PID: 9575 Comm: syz-executor1 Not tainted 4.19.0+ #312
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
RIP: 0010:icmp_timeout_obj_to_nlattr+0x77/0x170 net/netfilter/nf_conntrack_proto_icmp.c:297

Fixes: c779e849608a ("netfilter: conntrack: remove get_timeout() indirection")
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Zubin Mithra <zsm@chromium.org>
Signed-off-by: Sasha Levin (Microsoft) <sashal@kernel.org>
---
net/netfilter/nfnetlink_cttimeout.c | 46 +++++++++++++++++++++++++----
1 file changed, 40 insertions(+), 6 deletions(-)

diff --git a/net/netfilter/nfnetlink_cttimeout.c b/net/netfilter/nfnetlink_cttimeout.c
index a30f8ba4b89a..1dc4ea327cbe 100644
--- a/net/netfilter/nfnetlink_cttimeout.c
+++ b/net/netfilter/nfnetlink_cttimeout.c
@@ -392,7 +392,8 @@ err:
static int
cttimeout_default_fill_info(struct net *net, struct sk_buff *skb, u32 portid,
u32 seq, u32 type, int event,
- const struct nf_conntrack_l4proto *l4proto)
+ const struct nf_conntrack_l4proto *l4proto,
+ const unsigned int *timeouts)
{
struct nlmsghdr *nlh;
struct nfgenmsg *nfmsg;
@@ -421,7 +422,7 @@ cttimeout_default_fill_info(struct net *net, struct sk_buff *skb, u32 portid,
if (!nest_parms)
goto nla_put_failure;

- ret = l4proto->ctnl_timeout.obj_to_nlattr(skb, NULL);
+ ret = l4proto->ctnl_timeout.obj_to_nlattr(skb, timeouts);
if (ret < 0)
goto nla_put_failure;

@@ -444,6 +445,7 @@ static int cttimeout_default_get(struct net *net, struct sock *ctnl,
struct netlink_ext_ack *extack)
{
const struct nf_conntrack_l4proto *l4proto;
+ unsigned int *timeouts = NULL;
struct sk_buff *skb2;
int ret, err;
__u16 l3num;
@@ -456,12 +458,44 @@ static int cttimeout_default_get(struct net *net, struct sock *ctnl,
l4num = nla_get_u8(cda[CTA_TIMEOUT_L4PROTO]);
l4proto = nf_ct_l4proto_find_get(l3num, l4num);

- /* This protocol is not supported, skip. */
- if (l4proto->l4proto != l4num) {
- err = -EOPNOTSUPP;
+ err = -EOPNOTSUPP;
+ if (l4proto->l4proto != l4num)
goto err;
+
+ switch (l4proto->l4proto) {
+ case IPPROTO_ICMP:
+ timeouts = &net->ct.nf_ct_proto.icmp.timeout;
+ break;
+ case IPPROTO_TCP:
+ timeouts = net->ct.nf_ct_proto.tcp.timeouts;
+ break;
+ case IPPROTO_UDP:
+ timeouts = net->ct.nf_ct_proto.udp.timeouts;
+ break;
+ case IPPROTO_DCCP:
+#ifdef CONFIG_NF_CT_PROTO_DCCP
+ timeouts = net->ct.nf_ct_proto.dccp.dccp_timeout;
+#endif
+ break;
+ case IPPROTO_ICMPV6:
+ timeouts = &net->ct.nf_ct_proto.icmpv6.timeout;
+ break;
+ case IPPROTO_SCTP:
+#ifdef CONFIG_NF_CT_PROTO_SCTP
+ timeouts = net->ct.nf_ct_proto.sctp.timeouts;
+#endif
+ break;
+ case 255:
+ timeouts = &net->ct.nf_ct_proto.generic.timeout;
+ break;
+ default:
+ WARN_ON_ONCE(1);
+ break;
}

+ if (!timeouts)
+ goto err;
+
skb2 = nlmsg_new(NLMSG_DEFAULT_SIZE, GFP_KERNEL);
if (skb2 == NULL) {
err = -ENOMEM;
@@ -472,7 +506,7 @@ static int cttimeout_default_get(struct net *net, struct sock *ctnl,
nlh->nlmsg_seq,
NFNL_MSG_TYPE(nlh->nlmsg_type),
IPCTNL_MSG_TIMEOUT_DEFAULT_SET,
- l4proto);
+ l4proto, timeouts);
if (ret <= 0) {
kfree_skb(skb2);
err = -ENOMEM;
--
2.19.1


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