From: Wei Liu <wei.liu2@citrix.com>
Date: Tue, 27 Mar 2018 11:04:20 +0000 (+0100)
Subject: x86/vpci: validate data first in register_vpci_mmcfg_handler
X-Git-Tag: archive/raspbian/4.11.1-1+rpi1~1^2~66^2~312
X-Git-Url: https://dgit.raspbian.org/?a=commitdiff_plain;h=0e8e4a4437402bb53aa41081912ef14021ebb6ea;p=xen.git

x86/vpci: validate data first in register_vpci_mmcfg_handler

Avoid the need to deallocate memory when the data is invalid. It has
the benefit to not fragment memory in Xen.

Signed-off-by: Wei Liu <wei.liu2@citrix.com>
Reviewed-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Jan Beulich <jbeulich@suse.com>
---

diff --git a/xen/arch/x86/hvm/io.c b/xen/arch/x86/hvm/io.c
index 556810c126..9af5e3fee6 100644
--- a/xen/arch/x86/hvm/io.c
+++ b/xen/arch/x86/hvm/io.c
@@ -511,18 +511,16 @@ int register_vpci_mmcfg_handler(struct domain *d, paddr_t addr,
                                 unsigned int start_bus, unsigned int end_bus,
                                 unsigned int seg)
 {
-    struct hvm_mmcfg *mmcfg, *new = xmalloc(struct hvm_mmcfg);
+    struct hvm_mmcfg *mmcfg, *new;
 
     ASSERT(is_hardware_domain(d));
 
-    if ( !new )
-        return -ENOMEM;
-
     if ( start_bus > end_bus )
-    {
-        xfree(new);
         return -EINVAL;
-    }
+
+    new = xmalloc(struct hvm_mmcfg);
+    if ( !new )
+        return -ENOMEM;
 
     new->addr = addr + (start_bus << 20);
     new->start_bus = start_bus;