ipvs: Fix uninit-value in do_ip_vs_set_ctl()

[ Upstream commit c5a8a8498eed1c164afc94f50a939c1a10abf8ad ]

do_ip_vs_set_ctl() is referencing uninitialized stack value when `len` is
zero. Fix it.

Reported-by: syzbot+23b5f9e7caf61d9a3898@syzkaller.appspotmail.com
Link: https://syzkaller.appspot.com/bug?id=46ebfb92a8a812621a001ef04d90dfa459520fe2
Suggested-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Acked-by: Julian Anastasov <ja@ssi.bg>
Reviewed-by: Simon Horman <horms@verge.net.au>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/net/netfilter/ipvs/ip_vs_ctl.c b/net/netfilter/ipvs/ip_vs_ctl.c
index 33125fc009cfde20a257bee4559c51388eb9de27..ba9e711f7e3d66651df72d581abd9db493027b09 100644 (file)
--- a/net/netfilter/ipvs/ip_vs_ctl.c
+++ b/net/netfilter/ipvs/ip_vs_ctl.c
@@ -2424,6 +2424,10 @@ 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;
@@ -2500,9 +2504,6 @@ 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: