inet_diag: fix access to tcp cc information
Two different problems are fixed here :
1) inet_sk_diag_fill() might be called without socket lock held.
icsk->icsk_ca_ops can change under us and module be unloaded.
-> Access to freed memory.
Fix this using rcu_read_lock() to prevent module unload.
2) Some TCP Congestion Control modules provide information
but again this is not safe against icsk->icsk_ca_ops
change and nla_put() errors were ignored. Some sockets
could not get the additional info if skb was almost full.
Fix this by returning a status from get_info() handlers and
using rcu protection as well.
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv4/tcp_dctcp.c b/net/ipv4/tcp_dctcp.c
index b504371..4376016 100644
--- a/net/ipv4/tcp_dctcp.c
+++ b/net/ipv4/tcp_dctcp.c
@@ -277,7 +277,7 @@
}
}
-static void dctcp_get_info(struct sock *sk, u32 ext, struct sk_buff *skb)
+static int dctcp_get_info(struct sock *sk, u32 ext, struct sk_buff *skb)
{
const struct dctcp *ca = inet_csk_ca(sk);
@@ -297,8 +297,9 @@
info.dctcp_ab_tot = ca->acked_bytes_total;
}
- nla_put(skb, INET_DIAG_DCTCPINFO, sizeof(info), &info);
+ return nla_put(skb, INET_DIAG_DCTCPINFO, sizeof(info), &info);
}
+ return 0;
}
static struct tcp_congestion_ops dctcp __read_mostly = {