Thread (10 messages) 10 messages, 5 authors, 2020-08-28

[Linux-kernel-mentees] [PATCH net-next v2] ipvs: Fix uninit-value in do_ip_vs_set_ctl()

From: Peilin Ye <hidden>
Date: 2020-08-11 07:49:21
Also in: lkml, lvs-devel, netdev, netfilter-devel
Subsystem: ipvs, netfilter, networking [general], the rest · Maintainers: Simon Horman, Julian Anastasov, Pablo Neira Ayuso, Florian Westphal, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds

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 <redacted>
---
Changes in v2:
    - Target net-next tree. (Suggested by Julian Anastasov [off-list ref])
    - Reject all `len == 0` requests except `IP_VS_SO_SET_FLUSH`, instead
      of initializing `arg`. (Suggested by Cong Wang
      [off-list ref], Julian Anastasov [off-list ref])

 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

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