From 4f97e8708512462e87d2f1f1bdeb8cf55ce10e5a Mon Sep 17 00:00:00 2001 From: "H.J. Lu" 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 + . */ + +#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 -- GitLab