[xen master] pirq_cleanup_check() leaks

[patchbot@xxxxxxx]

commit daa90dfea9175c07f13d1a2d901857b2dd14d080
Author:     Jan Beulich <jbeulich@xxxxxxxx>
AuthorDate: Tue Jul 2 08:35:56 2024 +0200
Commit:     Jan Beulich <jbeulich@xxxxxxxx>
CommitDate: Tue Jul 2 08:35:56 2024 +0200

    pirq_cleanup_check() leaks
    
    Its original introduction had two issues: For one the "common" part of
    the checks (carried out in the macro) was inverted. And then after
    removal from the radix tree the structure wasn't scheduled for freeing.
    (All structures still left in the radix tree would be freed upon domain
    destruction, though.)
    
    For the freeing to be safe even if it didn't use RCU (i.e. to avoid use-
    after-free), re-arrange checks/operations in evtchn_close(), such that
    the pointer wouldn't be used anymore after calling pirq_cleanup_check()
    (noting that unmap_domain_pirq_emuirq() itself calls the function in the
    success case).
    
    Fixes: c24536b636f2 ("replace d->nr_pirqs sized arrays with radix tree")
    Fixes: 79858fee307c ("xen: fix hvm_domain_use_pirq's behavior")
    Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Release-Acked-By: Oleksii Kurochko <oleksii.kurochko@xxxxxxxxx>
---
 xen/arch/x86/irq.c         |  1 +
 xen/common/event_channel.c | 11 ++++++++---
 xen/include/xen/irq.h      |  2 +-
 3 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/irq.c b/xen/arch/x86/irq.c
index 9a611c79e0..017a94e311 100644
--- a/xen/arch/x86/irq.c
+++ b/xen/arch/x86/irq.c
@@ -1400,6 +1400,7 @@ void (pirq_cleanup_check)(struct pirq *pirq, struct 
domain *d)
 
     if ( radix_tree_delete(&d->pirq_tree, pirq->pirq) != pirq )
         BUG();
+    free_pirq_struct(pirq);
 }
 
 /* Flush all ready EOIs from the top of this CPU's pending-EOI stack. */
diff --git a/xen/common/event_channel.c b/xen/common/event_channel.c
index a67feff989..aac7d4b93f 100644
--- a/xen/common/event_channel.c
+++ b/xen/common/event_channel.c
@@ -710,9 +710,14 @@ int evtchn_close(struct domain *d1, int port1, bool guest)
             if ( !is_hvm_domain(d1) )
                 pirq_guest_unbind(d1, pirq);
             pirq->evtchn = 0;
-            pirq_cleanup_check(pirq, d1);
-            if ( is_hvm_domain(d1) && domain_pirq_to_irq(d1, pirq->pirq) > 0 )
-                unmap_domain_pirq_emuirq(d1, pirq->pirq);
+            if ( !is_hvm_domain(d1) ||
+                 domain_pirq_to_irq(d1, pirq->pirq) <= 0 ||
+                 unmap_domain_pirq_emuirq(d1, pirq->pirq) < 0 )
+                /*
+                 * The successful path of unmap_domain_pirq_emuirq() will have
+                 * called pirq_cleanup_check() already.
+                 */
+                pirq_cleanup_check(pirq, d1);
         }
         unlink_pirq_port(chn1, d1->vcpu[chn1->notify_vcpu_id]);
         break;
diff --git a/xen/include/xen/irq.h b/xen/include/xen/irq.h
index 17211f3399..ee45d19af8 100644
--- a/xen/include/xen/irq.h
+++ b/xen/include/xen/irq.h
@@ -186,7 +186,7 @@ extern struct pirq *pirq_get_info(struct domain *d, int 
pirq);
 void pirq_cleanup_check(struct pirq *pirq, struct domain *d);
 
 #define pirq_cleanup_check(pirq, d) \
-    ((pirq)->evtchn ? pirq_cleanup_check(pirq, d) : (void)0)
+    (!(pirq)->evtchn ? pirq_cleanup_check(pirq, d) : (void)0)
 
 extern void pirq_guest_eoi(struct pirq *pirq);
 extern void desc_guest_eoi(struct irq_desc *desc, struct pirq *pirq);
--
generated by git-patchbot for /home/xen/git/xen.git#master