[Xen-devel] [PATCH] don't put dom0 console info directly after start_info data

[Juergen Gross <jgross@xxxxxxxx>]

The console information of dom0 is living in the same memory page as the
start_info data. Don't put the console data directly after the start_info
to leave some room for future structure enlargements. Otherwise a dom0
with a newer start_info layout than the hypervisor could interprete
console data as part of the start_info data.

Before commit 50bd1f0825339dfacde471df7664729216fc46e3 there used to be a
padding at the end of start_info, but this was removed as it was regarded
to be not necessary.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 xen/arch/x86/domain_build.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/domain_build.c b/xen/arch/x86/domain_build.c
index d76707f..065406b 100644
--- a/xen/arch/x86/domain_build.c
+++ b/xen/arch/x86/domain_build.c
@@ -1462,9 +1462,11 @@ int __init construct_dom0(
     if ( cmdline != NULL )
         strlcpy((char *)si->cmd_line, cmdline, sizeof(si->cmd_line));
 
-    if ( fill_console_start_info((void *)(si + 1)) )
+    if ( fill_console_start_info((void *)si + PAGE_SIZE -
+                                 sizeof(struct dom0_vga_console_info)) )
     {
-        si->console.dom0.info_off  = sizeof(struct start_info);
+        si->console.dom0.info_off  =
+            PAGE_SIZE - sizeof(struct dom0_vga_console_info);
         si->console.dom0.info_size = sizeof(struct dom0_vga_console_info);
     }
 
-- 
2.1.4


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