* [PATCH net] netlink: extack needs to be reset each time through loop
@ 2018-01-10 21:00 David Ahern
2018-01-15 18:50 ` David Miller
0 siblings, 1 reply; 2+ messages in thread
From: David Ahern @ 2018-01-10 21:00 UTC (permalink / raw)
To: netdev, johannes.berg; +Cc: David Ahern
syzbot triggered the WARN_ON in netlink_ack testing the bad_attr value.
The problem is that netlink_rcv_skb loops over the skb repeatedly invoking
the callback and without resetting the extack leaving potentially stale
data. Initializing each time through avoids the WARN_ON.
Fixes: 2d4bc93368f5a ("netlink: extended ACK reporting")
Reported-by: syzbot+315fa6766d0f7c359327@syzkaller.appspotmail.com
Signed-off-by: David Ahern <dsahern@gmail.com>
---
net/netlink/af_netlink.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 972bfe113043..ee8252d7b3d4 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -2417,7 +2417,7 @@ int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
struct nlmsghdr *,
struct netlink_ext_ack *))
{
- struct netlink_ext_ack extack = {};
+ struct netlink_ext_ack extack;
struct nlmsghdr *nlh;
int err;
@@ -2438,6 +2438,7 @@ int netlink_rcv_skb(struct sk_buff *skb, int (*cb)(struct sk_buff *,
if (nlh->nlmsg_type < NLMSG_MIN_TYPE)
goto ack;
+ memset(&extack, 0, sizeof(extack));
err = cb(skb, nlh, &extack);
if (err == -EINTR)
goto skip;
--
2.11.0
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH net] netlink: extack needs to be reset each time through loop
2018-01-10 21:00 [PATCH net] netlink: extack needs to be reset each time through loop David Ahern
@ 2018-01-15 18:50 ` David Miller
0 siblings, 0 replies; 2+ messages in thread
From: David Miller @ 2018-01-15 18:50 UTC (permalink / raw)
To: dsahern; +Cc: netdev, johannes.berg
From: David Ahern <dsahern@gmail.com>
Date: Wed, 10 Jan 2018 13:00:39 -0800
> syzbot triggered the WARN_ON in netlink_ack testing the bad_attr value.
> The problem is that netlink_rcv_skb loops over the skb repeatedly invoking
> the callback and without resetting the extack leaving potentially stale
> data. Initializing each time through avoids the WARN_ON.
>
> Fixes: 2d4bc93368f5a ("netlink: extended ACK reporting")
> Reported-by: syzbot+315fa6766d0f7c359327@syzkaller.appspotmail.com
> Signed-off-by: David Ahern <dsahern@gmail.com>
Applied and queued up for -stable, thanks David.
^ permalink raw reply [flat|nested] 2+ messages in thread
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