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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        syzbot+23b5f9e7caf61d9a3898@syzkaller.appspotmail.com,
        Julian Anastasov <ja@ssi.bg>,
        Peilin Ye <yepeilin.cs@gmail.com>,
        Simon Horman <horms@verge.net.au>,
        Pablo Neira Ayuso <pablo@netfilter.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 4.9 130/139] ipvs: Fix uninit-value in do_ip_vs_set_ctl()
Date:   Tue, 27 Oct 2020 14:50:24 +0100
Message-Id: <20201027134908.324688782@linuxfoundation.org>
In-Reply-To: <20201027134902.130312227@linuxfoundation.org>
References: <20201027134902.130312227@linuxfoundation.org>
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From: Peilin Ye <yepeilin.cs@gmail.com>

[ 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>
---
 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