From: Hangyu Hua hbh25y@gmail.com

stable inclusion from stable-v4.19.254 commit fdb4fba1ba8512fa579a9d091dcb6c410f82f96a category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/I5JMHA CVE: CVE-2022-36879

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[ Upstream commit f85daf0e725358be78dfd208dea5fd665d8cb901 ]

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: 80c802f3073e ("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 --- net/xfrm/xfrm_policy.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c index e9aea82f370d..408e3f34d16c 100644 --- a/net/xfrm/xfrm_policy.c +++ b/net/xfrm/xfrm_policy.c @@ -1703,8 +1703,10 @@ static int xfrm_expand_policies(const struct flowi *fl, u16 family, *num_xfrms = 0; return 0; } - if (IS_ERR(pols[0])) + if (IS_ERR(pols[0])) { + *num_pols = 0; return PTR_ERR(pols[0]); + }

*num_xfrms = pols[0]->xfrm_nr;

@@ -1719,6 +1721,7 @@ 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)++;