From 4f97e8708512462e87d2f1f1bdeb8cf55ce10e5a Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Fri, 1 Feb 2019 12:23:23 -0800
Subject: [PATCH] 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)
---
.../x86_64/multiarch/strcpy-sse2-unaligned.S | 4 +-
sysdeps/x86_64/multiarch/strcpy-ssse3.S | 6 +-
sysdeps/x86_64/x32/Makefile | 2 +-
sysdeps/x86_64/x32/tst-size_t-strncpy.c | 58 +++++++++++++++++++
4 files changed, 64 insertions(+), 6 deletions(-)
create mode 100644 sysdeps/x86_64/x32/tst-size_t-strncpy.c
diff --git a/sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S b/sysdeps/x86_64/multiarch/strcpy-sse2-unaligned.S
index 72bf7e85..50aca22d 100644
--- 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 9858d0c4..0a62814a 100644
--- 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 $0, (%rcx)
diff --git a/sysdeps/x86_64/x32/Makefile b/sysdeps/x86_64/x32/Makefile
index db302839..2a9e20a9 100644
--- a/sysdeps/x86_64/x32/Makefile
+++ b/sysdeps/x86_64/x32/Makefile
@@ -8,7 +8,7 @@ endif
ifeq ($(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
index 00000000..4dec71e6
--- /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>
--
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