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Subject[PATCH 4.9 46/61] xfrm: fix a warning in xfrm_policy_insert_list
Date
From: Xin Long <lucien.xin@gmail.com>

commit ed17b8d377eaf6b4a01d46942b4c647378a79bdd upstream.

This waring can be triggered simply by:

# ip xfrm policy update src 192.168.1.1/24 dst 192.168.1.2/24 dir in \
priority 1 mark 0 mask 0x10 #[1]
# ip xfrm policy update src 192.168.1.1/24 dst 192.168.1.2/24 dir in \
priority 2 mark 0 mask 0x1 #[2]
# ip xfrm policy update src 192.168.1.1/24 dst 192.168.1.2/24 dir in \
priority 2 mark 0 mask 0x10 #[3]

Then dmesg shows:

[ ] WARNING: CPU: 1 PID: 7265 at net/xfrm/xfrm_policy.c:1548
[ ] RIP: 0010:xfrm_policy_insert_list+0x2f2/0x1030
[ ] Call Trace:
[ ] xfrm_policy_inexact_insert+0x85/0xe50
[ ] xfrm_policy_insert+0x4ba/0x680
[ ] xfrm_add_policy+0x246/0x4d0
[ ] xfrm_user_rcv_msg+0x331/0x5c0
[ ] netlink_rcv_skb+0x121/0x350
[ ] xfrm_netlink_rcv+0x66/0x80
[ ] netlink_unicast+0x439/0x630
[ ] netlink_sendmsg+0x714/0xbf0
[ ] sock_sendmsg+0xe2/0x110

The issue was introduced by Commit 7cb8a93968e3 ("xfrm: Allow inserting
policies with matching mark and different priorities"). After that, the
policies [1] and [2] would be able to be added with different priorities.

However, policy [3] will actually match both [1] and [2]. Policy [1]
was matched due to the 1st 'return true' in xfrm_policy_mark_match(),
and policy [2] was matched due to the 2nd 'return true' in there. It
caused WARN_ON() in xfrm_policy_insert_list().

This patch is to fix it by only (the same value and priority) as the
same policy in xfrm_policy_mark_match().

Thanks to Yuehaibing, we could make this fix better.

v1->v2:
- check policy->mark.v == pol->mark.v only without mask.

Fixes: 7cb8a93968e3 ("xfrm: Allow inserting policies with matching mark and different priorities")
Reported-by: Xiumei Mu <xmu@redhat.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
net/xfrm/xfrm_policy.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)

--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -757,12 +757,7 @@ static void xfrm_policy_requeue(struct x
static bool xfrm_policy_mark_match(struct xfrm_policy *policy,
struct xfrm_policy *pol)
{
- u32 mark = policy->mark.v & policy->mark.m;
-
- if (policy->mark.v == pol->mark.v && policy->mark.m == pol->mark.m)
- return true;
-
- if ((mark & pol->mark.m) == pol->mark.v &&
+ if (policy->mark.v == pol->mark.v &&
policy->priority == pol->priority)
return true;


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