netdev - [PATCH iproute2] libnetlink: __rtnl_talk_iov should only loop max iovlen times

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Message-Id: <20180301224308.2629-1-dsahern@gmail.com>
Date:   Thu,  1 Mar 2018 14:43:08 -0800
From:   David Ahern <dsahern@...il.com>
To:     stephen@...workplumber.org
Cc:     u9012063@...il.com, netdev@...r.kernel.org, chrism@...lanox.com,
        David Ahern <dsahern@...il.com>
Subject: [PATCH iproute2] libnetlink: __rtnl_talk_iov should only loop max iovlen times

William reported ip hanging and bisected to a recent commit for batching
allowing more than 1 command to be sent per message. The loop over
recvmsg should never cycle more than iovlen times -- 1 response for
each command in the message.

Fixes: 72a2ff3916e5 ("lib/libnetlink: Add a new function rtnl_talk_iov")
Signed-off-by: David Ahern <dsahern@...il.com>
---
 lib/libnetlink.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/lib/libnetlink.c b/lib/libnetlink.c
index 7ca47b22581a..8a7efaeb3cd3 100644
--- a/lib/libnetlink.c
+++ b/lib/libnetlink.c
@@ -670,8 +670,9 @@ static int __rtnl_talk_iov(struct rtnl_handle *rtnl, struct iovec *iov,
 						free(buf);
 					if (h->nlmsg_seq == seq)
 						return 0;
-					else
+					else if (i < iovlen)
 						goto next;
+					return 0;
 				}
 
 				if (rtnl->proto != NETLINK_SOCK_DIAG &&
-- 
2.11.0