do_ip_vs_set_ctl() is referencing uninitialized stack value when `len` is zero. Fix it. Reported-by: syzbot+23b5f9e7caf61d9a3898@xxxxxxxxxxxxxxxxxxxxxxxxx Link: https://syzkaller.appspot.com/bug?id=46ebfb92a8a812621a001ef04d90dfa459520fe2 Suggested-by: Julian Anastasov <ja@xxxxxx> Signed-off-by: Peilin Ye <yepeilin.cs@xxxxxxxxx> --- Changes in v2: - Target net-next tree. (Suggested by Julian Anastasov <ja@xxxxxx>) - Reject all `len == 0` requests except `IP_VS_SO_SET_FLUSH`, instead of initializing `arg`. (Suggested by Cong Wang <xiyou.wangcong@xxxxxxxxx>, Julian Anastasov <ja@xxxxxx>) net/netfilter/ipvs/ip_vs_ctl.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c index 412656c34f20..beeafa42aad7 100644 --- a/net/netfilter/ipvs/ip_vs_ctl.c +++ b/net/netfilter/ipvs/ip_vs_ctl.c @@ -2471,6 +2471,10 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len) /* Set timeout values for (tcp tcpfin udp) */ ret = ip_vs_set_timeout(ipvs, (struct ip_vs_timeout_user *)arg); goto out_unlock; + } else if (!len) { + /* No more commands with len == 0 below */ + ret = -EINVAL; + goto out_unlock; } usvc_compat = (struct ip_vs_service_user *)arg; @@ -2547,9 +2551,6 @@ do_ip_vs_set_ctl(struct sock *sk, int cmd, void __user *user, unsigned int len) break; case IP_VS_SO_SET_DELDEST: ret = ip_vs_del_dest(svc, &udest); - break; - default: - ret = -EINVAL; } out_unlock: -- 2.25.1
