libs/guest: Fix resource leaks in xc_core_arch_map_p2m_tree_rw()

Edwin, with the help of GCC's -fanalyzer, identified that p2m_frame_list_list
gets leaked.  What fanalyzer can't see is that the live_p2m_frame_list_list
and live_p2m_frame_list foreign mappings are leaked too.

Rework the logic so the out path is executed unconditionally, which cleans up
all the intermediate allocations/mappings appropriately.

Fixes: bd7a29c3d0 ("tools/libs/ctrl: fix xc_core_arch_map_p2m() to support linear p2m table")
Reported-by: Edwin Török <edwin.torok@cloud.com>
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
master commit: 1868d7f226
master date: 2023-02-27 15:51:23 +0000

tools/libs/guest/xg_core_x86.c

@@ -229,11 +229,11 @@ xc_core_arch_map_p2m_tree_rw(xc_interface *xch, struct domain_info_context *dinf
                              uint32_t dom, shared_info_any_t *live_shinfo)
 {
     /* Double and single indirect references to the live P2M table */
-    xen_pfn_t *live_p2m_frame_list_list;
+    xen_pfn_t *live_p2m_frame_list_list = NULL;
     xen_pfn_t *live_p2m_frame_list = NULL;
     /* Copies of the above. */
     xen_pfn_t *p2m_frame_list_list = NULL;
-    xen_pfn_t *p2m_frame_list;
+    xen_pfn_t *p2m_frame_list = NULL;
 
     int err;
     int i;
@@ -297,8 +297,6 @@ xc_core_arch_map_p2m_tree_rw(xc_interface *xch, struct domain_info_context *dinf
 
     dinfo->p2m_frames = P2M_FL_ENTRIES;
 
-    return p2m_frame_list;
-
  out:
     err = errno;
 
@@ -312,7 +310,7 @@ xc_core_arch_map_p2m_tree_rw(xc_interface *xch, struct domain_info_context *dinf
 
     errno = err;
 
-    return NULL;
+    return p2m_frame_list;
 }
 
 static int