4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Tom Herbert <tom@xxxxxxxxxxxxxx>
commit 581e7226a5d43f629eb6399a121f85f6a15f81be upstream.
TCP sockets for IPv4 and IPv6 that are not listeners or in closed
stated are allowed to be attached to a KCM mux.
Fixes: ab7ac4eb9832 ("kcm: Kernel Connection Multiplexor module")
Reported-by: syzbot+8865eaff7f9acd593945@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Tom Herbert <tom@xxxxxxxxxxxxxx>
Reviewed-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/kcm/kcmsock.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
--- a/net/kcm/kcmsock.c
+++ b/net/kcm/kcmsock.c
@@ -1381,8 +1381,13 @@ static int kcm_attach(struct socket *soc
if (!csk)
return -EINVAL;
- /* We must prevent loops or risk deadlock ! */
- if (csk->sk_family == PF_KCM)
+ /* Only allow TCP sockets to be attached for now */
+ if ((csk->sk_family != AF_INET && csk->sk_family != AF_INET6) ||
+ csk->sk_protocol != IPPROTO_TCP)
+ return -EOPNOTSUPP;
+
+ /* Don't allow listeners or closed sockets */
+ if (csk->sk_state == TCP_LISTEN || csk->sk_state == TCP_CLOSE)
return -EOPNOTSUPP;
psock = kmem_cache_zalloc(kcm_psockp, GFP_KERNEL);