From 8633e2951d8eba59755c82ef10099ed47eafd474 Mon Sep 17 00:00:00 2001

From: Laszlo Ersek <lersek@redhat.com>

Date: Fri, 2 Mar 2018 19:09:24 +0100

Subject: [PATCH 3/3] BaseTools/GenVtf: silence false "stringop-overflow"

 warning with memcpy()

gcc-8 (which is part of Fedora 28) enables the new warning

"-Wstringop-overflow" in "-Wall". This warning is documented in detail at

<https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html>; the

introduction says

> Warn for calls to string manipulation functions such as memcpy and

> strcpy that are determined to overflow the destination buffer.

It breaks the BaseTools build with:

> GenVtf.c: In function 'ConvertVersionInfo':

> GenVtf.c:132:7: error: 'strncpy' specified bound depends on the length

> of the source argument [-Werror=stringop-overflow=]

>        strncpy (TemStr + 4 - Length, Str, Length);

>        ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

> GenVtf.c:130:14: note: length computed here

>      Length = strlen(Str);

>               ^~~~~~~~~~~

It is a false positive because, while the bound equals the length of the

source argument, the destination pointer is moved back towards the

beginning of the destination buffer by the same amount (and this amount is

range-checked first, so we can't precede the start of the dest buffer).

Replace both strncpy() calls with memcpy().

Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>

Cc: Cole Robinson <crobinso@redhat.com>

Cc: Liming Gao <liming.gao@intel.com>

Cc: Paolo Bonzini <pbonzini@redhat.com>

Cc: Yonghong Zhu <yonghong.zhu@intel.com>

Reported-by: Cole Robinson <crobinso@redhat.com>

Contributed-under: TianoCore Contribution Agreement 1.1

Signed-off-by: Laszlo Ersek <lersek@redhat.com>

Message-Id: <20180302180924.4312-4-lersek@redhat.com>

Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

---

 BaseTools/Source/C/GenVtf/GenVtf.c | 4 ++--

 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/BaseTools/Source/C/GenVtf/GenVtf.c b/BaseTools/Source/C/GenVtf/GenVtf.c

index 2ae9a7be2c..0cd33e71e9 100644

--- a/BaseTools/Source/C/GenVtf/GenVtf.c

+++ b/BaseTools/Source/C/GenVtf/GenVtf.c

@@ -129,9 +129,9 @@ Returns:

   } else {

     Length = strlen(Str);

     if (Length < 4) {

-      strncpy (TemStr + 4 - Length, Str, Length);

+      memcpy (TemStr + 4 - Length, Str, Length);

     } else {

-      strncpy (TemStr, Str + Length - 4, 4);

+      memcpy (TemStr, Str + Length - 4, 4);

     }

     sscanf (

-- 

2.14.3