From 98dedfd83442b0d76dfec16973cdc1b475ecf198 Mon Sep 17 00:00:00 2001
From: Hangyu Hua <hbh25y@gmail.com>
Date: Wed, 1 Jun 2022 14:46:25 +0800
Subject: [PATCH] xfrm: xfrm_policy: fix a possible double xfrm_pols_put() in
xfrm_bundle_lookup()
Git-commit: f85daf0e725358be78dfd208dea5fd665d8cb901
Patch-mainline: v5.19-rc8
References: bsc#1201948 CVE-2022-36879
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: Denis Kirjanov <denis.kirjanov@suse.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 89bbe40736f9..722990d4e47d 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -1817,8 +1817,10 @@ 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;
@@ -1832,6 +1834,7 @@ 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)++;
--
2.16.4