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

stable inclusion
from stable-v4.19.254
commit fdb4fba1ba8512fa579a9d091dcb6c410f82f96a
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5J4T9


CVE: CVE-2022-36879

--------------------------------

[ Upstream commit f85daf0e ]

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.

This patch also fix an illegal address access. pols[0] will save a error
point when xfrm_policy_lookup fails. This lead to xfrm_pols_put to resolve
an illegal address in xfrm_bundle_lookup's error path.

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

Fixes: 80c802f3 ("xfrm: cache bundles instead of policies for outgoing flows")
Signed-off-by: Hangyu Hua <hbh25y@gmail.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Zhengchao Shao <shaozhengchao@huawei.com>
Reviewed-by: Xiu Jianfeng <xiujianfeng@huawei.com>
Reviewed-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Yongqiang Liu <liuyongqiang13@huawei.com>