x86/EFI: fix freeing of uninitialized pointer

The only valid response from the LocateHandle() call is EFI_BUFFER_TOO_SMALL,
so exit if we get anything else.  We pass a 0 size/NULL pointer buffer, so the
only other returns we will get is an error.  Return right away as there is
nothing to do.  Also return if there is an error allocating the buffer, as the
previous code path also allowed for an undefined pointer to be freed.

Signed-off-by: Roy Franz <roy.franz@linaro.org>
Re-structure the change.

Signed-off-by: Jan Beulich <jbeulich@suse.com>
master commit: c61690fb76f9a51a8c932d76929b67bd0940febe
master date: 2014-09-24 11:09:11 +0200

diff --git a/xen/arch/x86/efi/boot.c b/xen/arch/x86/efi/boot.c
index 0dd935cd1936019905ce5c662cfeff53481d9660..704489251a5860761fb2834383284f1b7c4f7c1e 100644 (file)
--- a/xen/arch/x86/efi/boot.c
+++ b/xen/arch/x86/efi/boot.c
@@ -594,11 +594,12 @@ static void __init setup_efi_pci(void)
     struct efi_pci_rom *last = NULL;
 
     status = efi_bs->LocateHandle(ByProtocol, &pci_guid, NULL, &size, NULL);
-    if ( status == EFI_BUFFER_TOO_SMALL )
-        status = efi_bs->AllocatePool(EfiLoaderData, size, (void **)&handles);
-    if ( !EFI_ERROR(status) )
-        status = efi_bs->LocateHandle(ByProtocol, &pci_guid, NULL, &size,
-                                      handles);
+    if ( status != EFI_BUFFER_TOO_SMALL )
+        return;
+    status = efi_bs->AllocatePool(EfiLoaderData, size, (void **)&handles);
+    if ( EFI_ERROR(status) )
+        return;
+    status = efi_bs->LocateHandle(ByProtocol, &pci_guid, NULL, &size, handles);
     if ( EFI_ERROR(status) )
         size = 0;