[Xen-changelog] [xen master] x86/vpci: validate data first in register_vpci_mmcfg_handler

[patchbot@xxxxxxx]

commit 0e8e4a4437402bb53aa41081912ef14021ebb6ea
Author:     Wei Liu <wei.liu2@xxxxxxxxxx>
AuthorDate: Tue Mar 27 12:04:20 2018 +0100
Commit:     Wei Liu <wei.liu2@xxxxxxxxxx>
CommitDate: Tue Mar 27 16:29:46 2018 +0100

    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@xxxxxxxxxx>
    Reviewed-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
    Acked-by: Jan Beulich <jbeulich@xxxxxxxx>
---
 xen/arch/x86/hvm/io.c | 12 +++++-------
 1 file changed, 5 insertions(+), 7 deletions(-)

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;
--
generated by git-patchbot for /home/xen/git/xen.git#master

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