From b085cb9bbf274f3fc05cc3f8ad92da946d5210bd Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Fri, 1 Feb 2019 12:17:09 -0800 Subject: x86-64 memchr/wmemchr: 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 memchr/wmemchr 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/memchr.S: Use RDX_LP for length. Clear the upper 32 bits of RDX register. * sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-memchr. * sysdeps/x86_64/x32/test-size_t.h: New file. * sysdeps/x86_64/x32/tst-size_t-memchr.c: Likewise. (cherry picked from commit 97700a34f36721b11a754cf37a1cc40695ece1fd) --- ChangeLog | 10 +++++ NEWS | 7 ++++ sysdeps/x86_64/memchr.S | 7 +++- sysdeps/x86_64/x32/Makefile | 4 ++ sysdeps/x86_64/x32/test-size_t.h | 35 +++++++++++++++++ sysdeps/x86_64/x32/tst-size_t-memchr.c | 72 ++++++++++++++++++++++++++++++++++ 6 files changed, 133 insertions(+), 2 deletions(-) create mode 100644 sysdeps/x86_64/x32/test-size_t.h create mode 100644 sysdeps/x86_64/x32/tst-size_t-memchr.c diff --git a/ChangeLog b/ChangeLog index 399d162f03..c376a89cdc 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,13 @@ +2019-02-01 H.J. Lu + + [BZ #24097] + CVE-2019-6488 + * sysdeps/x86_64/memchr.S: Use RDX_LP for length. Clear the + upper 32 bits of RDX register. + * sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-memchr. + * sysdeps/x86_64/x32/test-size_t.h: New file. + * sysdeps/x86_64/x32/tst-size_t-memchr.c: Likewise. + 2018-12-31 Florian Weimer [BZ #24027] diff --git a/NEWS b/NEWS index f7536ac0d9..dcf8ba65e7 100644 --- a/NEWS +++ b/NEWS @@ -60,6 +60,12 @@ Security related changes: architecture could write beyond the target buffer, resulting in a buffer overflow. Reported by Andreas Schwab. + CVE-2019-6488: On x32, the size_t parameter may be passed in the lower + 32 bits of a 64-bit register with with non-zero upper 32 bit. When it + happened, accessing the 32-bit size_t value as the full 64-bit register + in the assembly string/memory functions would cause a buffer overflow. + Reported by H.J. Lu. + The following bugs are resolved with this release: [20116] nptl: use after free in pthread_create @@ -82,6 +88,7 @@ The following bugs are resolved with this release: [23196] string: __mempcpy_avx512_no_vzeroupper mishandles large copies (CVE-2018-11237) [24027] malloc: Integer overflow in realloc + [24097] Can't use 64-bit register for size_t in assembly codes for x32 (CVE-2019-6488) Version 2.24 diff --git a/sysdeps/x86_64/memchr.S b/sysdeps/x86_64/memchr.S index 132eacba8f..b8c30a6fe4 100644 --- a/sysdeps/x86_64/memchr.S +++ b/sysdeps/x86_64/memchr.S @@ -24,9 +24,12 @@ ENTRY(memchr) movd %rsi, %xmm1 mov %rdi, %rcx - +#ifdef __ILP32__ + /* Clear the upper 32 bits. */ + movl %edx, %edx +#endif punpcklbw %xmm1, %xmm1 - test %rdx, %rdx + test %RDX_LP, %RDX_LP jz L(return_null) punpcklbw %xmm1, %xmm1 diff --git a/sysdeps/x86_64/x32/Makefile b/sysdeps/x86_64/x32/Makefile index f2ebc24fb0..979273b3a8 100644 --- a/sysdeps/x86_64/x32/Makefile +++ b/sysdeps/x86_64/x32/Makefile @@ -4,3 +4,7 @@ ifeq ($(subdir),math) # 64-bit llround. Add -fno-builtin-lround to silence the compiler. CFLAGS-s_llround.c += -fno-builtin-lround endif + +ifeq ($(subdir),string) +tests += tst-size_t-memchr +endif diff --git a/sysdeps/x86_64/x32/test-size_t.h b/sysdeps/x86_64/x32/test-size_t.h new file mode 100644 index 0000000000..78a940863e --- /dev/null +++ b/sysdeps/x86_64/x32/test-size_t.h @@ -0,0 +1,35 @@ +/* Test string/memory functions 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_MAIN +#include + +/* On x32, parameter_t may be passed in a 64-bit register with the LEN + field in the lower 32 bits. When the LEN field of 64-bit register + is passed to string/memory function as the size_t parameter, only + the lower 32 bits can be used. */ +typedef struct +{ + union + { + size_t len; + void (*fn) (void); + }; + void *p; +} parameter_t; diff --git a/sysdeps/x86_64/x32/tst-size_t-memchr.c b/sysdeps/x86_64/x32/tst-size_t-memchr.c new file mode 100644 index 0000000000..ac77b86c08 --- /dev/null +++ b/sysdeps/x86_64/x32/tst-size_t-memchr.c @@ -0,0 +1,72 @@ +/* Test memchr 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 + . */ + +#ifndef WIDE +# define TEST_NAME "memchr" +#else +# define TEST_NAME "wmemchr" +#endif /* WIDE */ +#include "test-size_t.h" + +#ifndef WIDE +# define MEMCHR memchr +# define CHAR char +# define UCHAR unsigned char +#else +# include +# define MEMCHR wmemchr +# define CHAR wchar_t +# define UCHAR wchar_t +#endif /* WIDE */ + +IMPL (MEMCHR, 1) + +typedef CHAR * (*proto_t) (const CHAR*, int, size_t); + +static CHAR * +__attribute__ ((noinline, noclone)) +do_memchr (parameter_t a, parameter_t b) +{ + return CALL (&b, a.p, (uintptr_t) b.p, a.len); +} + +static int +test_main (void) +{ + test_init (); + + parameter_t src = { { page_size / sizeof (CHAR) }, buf2 }; + parameter_t c = { { 0 }, (void *) (uintptr_t) 0x12 }; + + int ret = 0; + FOR_EACH_IMPL (impl, 0) + { + c.fn = impl->fn; + CHAR *res = do_memchr (src, c); + if (res) + { + error (0, 0, "Wrong result in function %s: %p != NULL", + impl->name, res); + ret = 1; + } + } + + return ret ? EXIT_FAILURE : EXIT_SUCCESS; +} + +#include -- cgit 1.4.1