[PATCH] xfrm: xfrm_policy: fix a possible double xfrm_pols_put() in xfrm_bundle_lookup()

[Hangyu Hua]

xfrm_policy_lookup() will call xfrm_pol_hold_rcu() to get a refcount of
pols[0]. This refcount can be dropped in xfrm_expand_policies() when
xfrm_expand_policies() return error. pols[0]'s refcount is balanced in
here. But xfrm_bundle_lookup() will also call xfrm_pols_put() with
num_pols == 1 to drop this refcount when xfrm_expand_policies() return
error.

Fix this by setting num_pols = 0 in xfrm_expand_policies()'s error path.

Fixes: 80c802f3073e ("xfrm: cache bundles instead of policies for outgoing flows")
Signed-off-by: Hangyu Hua <hbh25y@xxxxxxxxx>
---
 net/xfrm/xfrm_policy.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index f1876ea61fdc..a511875ef523 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -2694,6 +2694,7 @@ static int xfrm_expand_policies(const struct flowi *fl, u16 family,
 		if (pols[1]) {
 			if (IS_ERR(pols[1])) {
 				xfrm_pols_put(pols, *num_pols);
+				*num_pols = 0;
 				return PTR_ERR(pols[1]);
 			}
 			(*num_pols)++;
-- 
2.25.1