[Xen-devel] [PATCH] x86/hvm: Fix rcu_unlock_domain call bypass

[Adrian Pop <apop@xxxxxxxxxxxxxxx>]

rcu_lock_current_domain is called at the beginning of do_altp2m_op, but
the altp2m_vcpu_enable_notify subop handler might skip calling
rcu_unlock_domain, possibly hanging the domain altogether.

Signed-off-by: Adrian Pop <apop@xxxxxxxxxxxxxxx>
---
 xen/arch/x86/hvm/hvm.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
index 205b4cb685..0af498a312 100644
--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -4534,12 +4534,18 @@ static int do_altp2m_op(
 
         if ( a.u.enable_notify.pad || a.domain != DOMID_SELF ||
              a.u.enable_notify.vcpu_id != curr->vcpu_id )
+        {
             rc = -EINVAL;
+            break;
+        }
 
         if ( !gfn_eq(vcpu_altp2m(curr).veinfo_gfn, INVALID_GFN) ||
              mfn_eq(get_gfn_query_unlocked(curr->domain,
                     a.u.enable_notify.gfn, &p2mt), INVALID_MFN) )
-            return -EINVAL;
+        {
+            rc = -EINVAL;
+            break;
+        }
 
         vcpu_altp2m(curr).veinfo_gfn = _gfn(a.u.enable_notify.gfn);
         altp2m_vcpu_update_vmfunc_ve(curr);
-- 
2.15.0


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