xen/domain: Disallow XENMEM_claim_pages on dying domains

XENMEM_claim_pages can be issued on a domain in the later stages of
domain_kill().  In that case, the claimed memory is leaked, as there's no way
to subsequently release the claim.

Claims are intended for use during domain construction; to reserve sufficient
RAM to construct the domain fully.  There's no legitimate reason to be calling
it on a dying domain.

Fixes: 65c9792df6 ("mmu: Introduce XENMEM_claim_pages (subop of memory ops)")
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Jan Beulich <jbeulich@suse.com>
master commit: 2379ca04fe
master date: 2025-12-17 17:35:24 +0000

xen/common/memory.c

@@ -1678,6 +1678,9 @@ long do_memory_op(unsigned long cmd, XEN_GUEST_HANDLE_PARAM(void) arg)
 
         rc = xsm_claim_pages(XSM_PRIV, d);
 
+        if ( !rc && d->is_dying )
+            rc = -EINVAL;
+
         if ( !rc )
             rc = domain_set_outstanding_pages(d, reservation.nr_extents);