From a107bd201f836b1d82e1a9086a2a48625ac1c0dd Mon Sep 17 00:00:00 2001
From: "H.J. Lu" <hjl.tools@gmail.com>
Date: Wed, 2 Mar 2022 13:52:42 -0800
Subject: [PATCH] x86-64 memcmp/wmemcmp: 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 memcmp/wmemcmp 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/memcmp-avx2-movbe.S: Use RDX_LP for
length. Clear the upper 32 bits of RDX register.
* sysdeps/x86_64/multiarch/memcmp-sse4.S: Likewise.
* sysdeps/x86_64/multiarch/memcmp-ssse3.S: Likewise.
* sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-memcmp and
tst-size_t-wmemcmp.
* sysdeps/x86_64/x32/tst-size_t-memcmp.c: New file.
* sysdeps/x86_64/x32/tst-size_t-wmemcmp.c: Likewise.
(cherry picked from commit b304fc201d2f6baf52ea790df8643e99772243cd)
---
sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S | 7 +-
sysdeps/x86_64/multiarch/memcmp-sse4.S | 9 ++-
sysdeps/x86_64/multiarch/memcmp-ssse3.S | 7 +-
sysdeps/x86_64/x32/Makefile | 4 +-
sysdeps/x86_64/x32/tst-size_t-memcmp.c | 76 ++++++++++++++++++++
sysdeps/x86_64/x32/tst-size_t-wmemcmp.c | 20 ++++++
6 files changed, 114 insertions(+), 9 deletions(-)
create mode 100644 sysdeps/x86_64/x32/tst-size_t-memcmp.c
create mode 100644 sysdeps/x86_64/x32/tst-size_t-wmemcmp.c
diff --git a/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S b/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S
index 30f764c3..e3a35b89 100644
--- a/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S
+++ b/sysdeps/x86_64/multiarch/memcmp-avx2-movbe.S
@@ -58,9 +58,12 @@
.section .text.avx,"ax",@progbits
ENTRY (MEMCMP)
# ifdef USE_AS_WMEMCMP
- shl $2, %rdx
+ shl $2, %RDX_LP
+# elif defined __ILP32__
+ /* Clear the upper 32 bits. */
+ movl %edx, %edx
# endif
- cmpq $VEC_SIZE, %rdx
+ cmp $VEC_SIZE, %RDX_LP
jb L(less_vec)
/* From VEC to 2 * VEC. No branch when size == VEC_SIZE. */
diff --git a/sysdeps/x86_64/multiarch/memcmp-sse4.S b/sysdeps/x86_64/multiarch/memcmp-sse4.S
index 8e164f2c..302900f5 100644
--- a/sysdeps/x86_64/multiarch/memcmp-sse4.S
+++ b/sysdeps/x86_64/multiarch/memcmp-sse4.S
@@ -42,13 +42,16 @@
.section .text.sse4.1,"ax",@progbits
ENTRY (MEMCMP)
# ifdef USE_AS_WMEMCMP
- shl $2, %rdx
+ shl $2, %RDX_LP
+# elif defined __ILP32__
+ /* Clear the upper 32 bits. */
+ mov %edx, %edx
# endif
pxor %xmm0, %xmm0
- cmp $79, %rdx
+ cmp $79, %RDX_LP
ja L(79bytesormore)
# ifndef USE_AS_WMEMCMP
- cmp $1, %rdx
+ cmp $1, %RDX_LP
je L(firstbyte)
# endif
add %rdx, %rsi
diff --git a/sysdeps/x86_64/multiarch/memcmp-ssse3.S b/sysdeps/x86_64/multiarch/memcmp-ssse3.S
index 6f76c641..69d030fc 100644
--- a/sysdeps/x86_64/multiarch/memcmp-ssse3.S
+++ b/sysdeps/x86_64/multiarch/memcmp-ssse3.S
@@ -33,9 +33,12 @@
atom_text_section
ENTRY (MEMCMP)
# ifdef USE_AS_WMEMCMP
- shl $2, %rdx
- test %rdx, %rdx
+ shl $2, %RDX_LP
+ test %RDX_LP, %RDX_LP
jz L(equal)
+# elif defined __ILP32__
+ /* Clear the upper 32 bits. */
+ mov %edx, %edx
# endif
mov %rdx, %rcx
mov %rdi, %rdx
diff --git a/sysdeps/x86_64/x32/Makefile b/sysdeps/x86_64/x32/Makefile
index 7d528889..ddec7f04 100644
--- a/sysdeps/x86_64/x32/Makefile
+++ b/sysdeps/x86_64/x32/Makefile
@@ -6,9 +6,9 @@ CFLAGS-s_llround.c += -fno-builtin-lround
endif
ifeq ($(subdir),string)
-tests += tst-size_t-memchr
+tests += tst-size_t-memchr tst-size_t-memcmp
endif
ifeq ($(subdir),wcsmbs)
-tests += tst-size_t-wmemchr
+tests += tst-size_t-wmemchr tst-size_t-wmemcmp
endif
diff --git a/sysdeps/x86_64/x32/tst-size_t-memcmp.c b/sysdeps/x86_64/x32/tst-size_t-memcmp.c
new file mode 100644
index 00000000..9bd6fdb4
--- /dev/null
+++ b/sysdeps/x86_64/x32/tst-size_t-memcmp.c
@@ -0,0 +1,76 @@
+/* Test memcmp 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_MAIN
+#ifdef WIDE
+# define TEST_NAME "wmemcmp"
+#else
+# define TEST_NAME "memcmp"
+#endif
+
+#include "test-size_t.h"
+
+#ifdef WIDE
+# include <inttypes.h>
+# include <wchar.h>
+
+# define MEMCMP wmemcmp
+# define CHAR wchar_t
+#else
+# define MEMCMP memcmp
+# define CHAR char
+#endif
+
+IMPL (MEMCMP, 1)
+
+typedef int (*proto_t) (const CHAR *, const CHAR *, size_t);
+
+static int
+__attribute__ ((noinline, noclone))
+do_memcmp (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 / sizeof (CHAR) }, buf1 };
+ parameter_t src = { { 0 }, buf2 };
+
+ memcpy (buf1, buf2, page_size);
+
+ int ret = 0;
+ FOR_EACH_IMPL (impl, 0)
+ {
+ src.fn = impl->fn;
+ int res = do_memcmp (dest, src);
+ 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>
diff --git a/sysdeps/x86_64/x32/tst-size_t-wmemcmp.c b/sysdeps/x86_64/x32/tst-size_t-wmemcmp.c
new file mode 100644
index 00000000..e8b5ffd0
--- /dev/null
+++ b/sysdeps/x86_64/x32/tst-size_t-wmemcmp.c
@@ -0,0 +1,20 @@
+/* Test wmemcmp 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 WIDE 1
+#include "tst-size_t-memcmp.c"
--
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