3.16.52-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
commit 1137b5e2529a8f5ca8ee709288ecba3e68044df2 upstream.
This is a fix for CVE-2017-16939 suitable for older stable branches.
The upstream fix is commit 1137b5e2529a8f5ca8ee709288ecba3e68044df2,
from which the following explanation is taken:
An independent security researcher, Mohamed Ghannam, has reported
this vulnerability to Beyond Security's SecuriTeam Secure Disclosure
program.
The xfrm_dump_policy_done function expects xfrm_dump_policy to
have been called at least once or it will crash. This can be
triggered if a dump fails because the target socket's receive
buffer is full.
It was not possible to define a 'start' callback for netlink dumps
until Linux 4.5, so instead add a check for the initialisation flag in
the 'done' callback.
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -1570,7 +1570,8 @@ static int xfrm_dump_policy_done(struct
struct xfrm_policy_walk *walk = (struct xfrm_policy_walk *) &cb->args[1];
struct net *net = sock_net(cb->skb->sk);
- xfrm_policy_walk_done(walk, net);
+ if (cb->args[0])
+ xfrm_policy_walk_done(walk, net);
return 0;
}