x86-64 strncpy: Properly handle the length parameter [BZ #24097]

On x32, the size_t parameter may be passed in the lower 32 bits of a
64-bit register with the non-zero upper 32 bits.  The string/memory
functions written in assembly can only use the lower 32 bits of a
64-bit register as length or must clear the upper 32 bits before using
the full 64-bit register for length.

This pach fixes strncpy for x32.  Tested on x86-64 and x32.  On x86-64,
libc.so is the same with and withou the fix.

	[BZ #24097]
	CVE-2019-6488
	* sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S: Use RDX_LP
	for length.
	* sysdeps/x86_64/multiarch/strcpy-ssse3.S: Likewise.
	* sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-strncpy.
	* sysdeps/x86_64/x32/tst-size_t-strncpy.c: New file.

(cherry picked from commit c7c54f65b080affb87a1513dee449c8ad6143c8b)

diff --git a/ChangeLog b/ChangeLog
index 210a4eb2e42579978f3e20051a4218ed633c8db9..d9caf55df4382463b311b740b515b1231259420e 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2019-02-01  H.J. Lu  <hongjiu.lu@intel.com>
+
+       [BZ #24097]
+       CVE-2019-6488
+       * sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S: Use RDX_LP
+       for length.
+       * sysdeps/x86_64/multiarch/strcpy-ssse3.S: Likewise.
+       * sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-strncpy.
+       * sysdeps/x86_64/x32/tst-size_t-strncpy.c: New file.
+
 2019-02-01  H.J. Lu  <hongjiu.lu@intel.com>
 
        [BZ #24097]

diff --git a/sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S b/sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S
index 72bf7e8586b7ea5f604a1627985d8dd2b35d5bca..50aca22d2ee7abbd1c084564d5dd3c5f138dce00 100644 (file)
--- a/sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S
+++ b/sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S
@@ -40,8 +40,8 @@
 .text
 ENTRY (STRCPY)
 #  ifdef USE_AS_STRNCPY
-       mov     %rdx, %r8
-       test    %r8, %r8
+       mov     %RDX_LP, %R8_LP
+       test    %R8_LP, %R8_LP
        jz      L(ExitZero)
 #  endif
        mov     %rsi, %rcx

diff --git a/sysdeps/x86_64/multiarch/strcpy-ssse3.S b/sysdeps/x86_64/multiarch/strcpy-ssse3.S
index 9858d0c4d5a49699a7287f598063488479019467..0a62814a06d3455a61e370649eabf8543b85b975 100644 (file)
--- a/sysdeps/x86_64/multiarch/strcpy-ssse3.S
+++ b/sysdeps/x86_64/multiarch/strcpy-ssse3.S
@@ -31,13 +31,13 @@ ENTRY (STRCPY)
 
        mov     %rsi, %rcx
 #  ifdef USE_AS_STRNCPY
-       mov     %rdx, %r8
+       mov     %RDX_LP, %R8_LP
 #  endif
        mov     %rdi, %rdx
 #  ifdef USE_AS_STRNCPY
-       test    %r8, %r8
+       test    %R8_LP, %R8_LP
        jz      L(Exit0)
-       cmp     $8, %r8
+       cmp     $8, %R8_LP
        jbe     L(StrncpyExit8Bytes)
 # endif
        cmpb    $0, (%rcx)

diff --git a/sysdeps/x86_64/x32/Makefile b/sysdeps/x86_64/x32/Makefile
index db30283977e26398e580c17af0c14fbaa086643d..2a9e20a90b35debc9d7e24f77f1a3a85433ae67e 100644 (file)
--- a/sysdeps/x86_64/x32/Makefile
+++ b/sysdeps/x86_64/x32/Makefile
@@ -8,7 +8,7 @@ endif
 ifeq ($(subdir),string)
 tests += tst-size_t-memchr tst-size_t-memcmp tst-size_t-memcpy \
         tst-size_t-memrchr tst-size_t-memset tst-size_t-strncasecmp \
-        tst-size_t-strncmp
+        tst-size_t-strncmp tst-size_t-strncpy
 endif
 
 ifeq ($(subdir),wcsmbs)

diff --git a/sysdeps/x86_64/x32/tst-size_t-strncpy.c b/sysdeps/x86_64/x32/tst-size_t-strncpy.c
new file mode 100644 (file)
index 0000000..4dec71e
--- /dev/null
+++ b/sysdeps/x86_64/x32/tst-size_t-strncpy.c
@@ -0,0 +1,58 @@
+/* Test strncpy with size_t in the lower 32 bits of 64-bit register.
+   Copyright (C) 2019 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#define TEST_NAME "strncpy"
+#include "test-size_t.h"
+
+IMPL (strncpy, 1)
+
+typedef char *(*proto_t) (char *, const char*, size_t);
+
+static void *
+__attribute__ ((noinline, noclone))
+do_strncpy (parameter_t a, parameter_t b)
+{
+  return CALL (&b, a.p, b.p, a.len);
+}
+
+static int
+test_main (void)
+{
+  test_init ();
+
+  parameter_t dest = { { page_size }, buf1 };
+  parameter_t src = { { 0 }, buf2 };
+
+  int ret = 0;
+  FOR_EACH_IMPL (impl, 0)
+    {
+      src.fn = impl->fn;
+      do_strncpy (dest, src);
+      int res = strncmp (dest.p, src.p, dest.len);
+      if (res)
+       {
+         error (0, 0, "Wrong result in function %s: %i != 0",
+                impl->name, res);
+         ret = 1;
+       }
+    }
+
+  return ret ? EXIT_FAILURE : EXIT_SUCCESS;
+}
+
+#include <support/test-driver.c>