[PATCH AUTOSEL 4.9 37/41] ipvs: Fix uninit-value in do_ip_vs_set_ctl()

[Sasha Levin <sashal@xxxxxxxxxx>]

From: Peilin Ye <yepeilin.cs@xxxxxxxxx>

[ Upstream commit c5a8a8498eed1c164afc94f50a939c1a10abf8ad ]

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>
Acked-by: Julian Anastasov <ja@xxxxxx>
Reviewed-by: Simon Horman <horms@xxxxxxxxxxxx>
Signed-off-by: Pablo Neira Ayuso <pablo@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 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 33125fc009cfd..ba9e711f7e3d6 100644
--- 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:
-- 
2.25.1