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

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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: 80c802f307 ("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>
This commit is contained in:
Hangyu Hua 2022-06-01 14:46:25 +08:00 committed by Steffen Klassert
parent 9f4fc18bf2
commit f85daf0e72
1 changed files with 4 additions and 1 deletions
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5
net/xfrm/xfrm_policy.c
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@ -2678,8 +2678,10 @@ 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;
@ -2694,6 +2696,7 @@ 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)++;