linux-kernel - [PATCH 3.12 055/119] ipv6: release dst in ping_v6

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Date:   Thu, 29 Sep 2016 12:24:51 +0200
From:   Jiri Slaby <jslaby@...e.cz>
To:     stable@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, Dave Jones <davej@...emonkey.org.uk>,
        Martin Lau <kafai@...com>,
        "David S . Miller" <davem@...emloft.net>,
        Jiri Slaby <jslaby@...e.cz>
Subject: [PATCH 3.12 055/119] ipv6: release dst in ping_v6_sendmsg

From: Dave Jones <davej@...emonkey.org.uk>

3.12-stable review patch.  If anyone has any objections, please let me know.

===============

[ Upstream commit 03c2778a938aaba0893f6d6cdc29511d91a79848 ]

Neither the failure or success paths of ping_v6_sendmsg release
the dst it acquires.  This leads to a flood of warnings from
"net/core/dst.c:288 dst_release" on older kernels that
don't have 8bf4ada2e21378816b28205427ee6b0e1ca4c5f1 backported.

That patch optimistically hoped this had been fixed post 3.10, but
it seems at least one case wasn't, where I've seen this triggered
a lot from machines doing unprivileged icmp sockets.

Cc: Martin Lau <kafai@...com>
Signed-off-by: Dave Jones <davej@...emonkey.org.uk>
Acked-by: Martin KaFai Lau <kafai@...com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Jiri Slaby <jslaby@...e.cz>
---
 net/ipv6/ping.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/net/ipv6/ping.c b/net/ipv6/ping.c
index f414af6cda43..1896e104116c 100644
--- a/net/ipv6/ping.c
+++ b/net/ipv6/ping.c
@@ -152,8 +152,10 @@ int ping_v6_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	rt = (struct rt6_info *) dst;
 
 	np = inet6_sk(sk);
-	if (!np)
-		return -EBADF;
+	if (!np) {
+		err = -EBADF;
+		goto dst_err_out;
+	}
 
 	if (!fl6.flowi6_oif && ipv6_addr_is_multicast(&fl6.daddr))
 		fl6.flowi6_oif = np->mcast_oif;
@@ -193,6 +195,9 @@ int ping_v6_sendmsg(struct kiocb *iocb, struct sock *sk, struct msghdr *msg,
 	}
 	release_sock(sk);
 
+dst_err_out:
+	dst_release(dst);
+
 	if (err)
 		return err;
 
-- 
2.10.0