From 97700a34f36721b11a754cf37a1cc40695ece1fd Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Mon, 21 Jan 2019 11:23:59 -0800 Subject: [PATCH] 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/multiarch/memchr-avx2.S: Likewise. * sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-memchr and tst-size_t-wmemchr. * sysdeps/x86_64/x32/test-size_t.h: New file. * sysdeps/x86_64/x32/tst-size_t-memchr.c: Likewise. * sysdeps/x86_64/x32/tst-size_t-wmemchr.c: Likewise. --- ChangeLog | 13 ++++++ NEWS | 6 +++ sysdeps/x86_64/memchr.S | 10 +++-- sysdeps/x86_64/multiarch/memchr-avx2.S | 8 +++- sysdeps/x86_64/x32/Makefile | 8 ++++ sysdeps/x86_64/x32/test-size_t.h | 35 ++++++++++++++++ sysdeps/x86_64/x32/tst-size_t-memchr.c | 72 +++++++++++++++++++++++++++++++++ sysdeps/x86_64/x32/tst-size_t-wmemchr.c | 20 +++++++++ 8 files changed, 167 insertions(+), 5 deletions(-) create mode 100644 sysdeps/x86_64/x32/test-size_t.h create mode 100644 sysdeps/x86_64/x32/tst-size_t-memchr.c create mode 100644 sysdeps/x86_64/x32/tst-size_t-wmemchr.c diff --git a/ChangeLog b/ChangeLog index d2d6185..e90b8a7 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,16 @@ +2019-01-21 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/multiarch/memchr-avx2.S: Likewise. + * sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-memchr and + tst-size_t-wmemchr. + * sysdeps/x86_64/x32/test-size_t.h: New file. + * sysdeps/x86_64/x32/tst-size_t-memchr.c: Likewise. + * sysdeps/x86_64/x32/tst-size_t-wmemchr.c: Likewise. + 2019-01-18 Florian Weimer [BZ #24112] diff --git a/NEWS b/NEWS index cc20102..7b3af11 100644 --- a/NEWS +++ b/NEWS @@ -101,6 +101,12 @@ Security related changes: denial of service due to resource exhaustion when processing getaddrinfo calls with crafted host names. Reported by Guido Vranken. + 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: [The release manager will add the list generated by diff --git a/sysdeps/x86_64/memchr.S b/sysdeps/x86_64/memchr.S index a6f3ebb..ec96365 100644 --- a/sysdeps/x86_64/memchr.S +++ b/sysdeps/x86_64/memchr.S @@ -34,12 +34,16 @@ ENTRY(MEMCHR) mov %edi, %ecx #ifdef USE_AS_WMEMCHR - test %rdx, %rdx + test %RDX_LP, %RDX_LP jz L(return_null) - shl $2, %rdx + shl $2, %RDX_LP #else +# 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 #endif diff --git a/sysdeps/x86_64/multiarch/memchr-avx2.S b/sysdeps/x86_64/multiarch/memchr-avx2.S index 9f98b7e..cfec165 100644 --- a/sysdeps/x86_64/multiarch/memchr-avx2.S +++ b/sysdeps/x86_64/multiarch/memchr-avx2.S @@ -40,16 +40,20 @@ ENTRY (MEMCHR) # ifndef USE_AS_RAWMEMCHR /* Check for zero length. */ - testq %rdx, %rdx + test %RDX_LP, %RDX_LP jz L(null) # endif movl %edi, %ecx /* Broadcast CHAR to YMM0. */ vmovd %esi, %xmm0 # ifdef USE_AS_WMEMCHR - shl $2, %rdx + shl $2, %RDX_LP vpbroadcastd %xmm0, %ymm0 # else +# ifdef __ILP32__ + /* Clear the upper 32 bits. */ + movl %edx, %edx +# endif vpbroadcastb %xmm0, %ymm0 # endif /* Check if we may cross page boundary with one vector load. */ diff --git a/sysdeps/x86_64/x32/Makefile b/sysdeps/x86_64/x32/Makefile index f2ebc24..7d52888 100644 --- a/sysdeps/x86_64/x32/Makefile +++ b/sysdeps/x86_64/x32/Makefile @@ -4,3 +4,11 @@ ifeq ($(subdir),math) # 64-bit llround. Add -fno-builtin-lround to silence the compiler. CFLAGS-s_llround.c += -fno-builtin-lround endif + +ifeq ($(subdir),string) +tests += tst-size_t-memchr +endif + +ifeq ($(subdir),wcsmbs) +tests += tst-size_t-wmemchr +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 0000000..78a9408 --- /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 0000000..29a3daf --- /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 diff --git a/sysdeps/x86_64/x32/tst-size_t-wmemchr.c b/sysdeps/x86_64/x32/tst-size_t-wmemchr.c new file mode 100644 index 0000000..877801d --- /dev/null +++ b/sysdeps/x86_64/x32/tst-size_t-wmemchr.c @@ -0,0 +1,20 @@ +/* Test wmemchr 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 WIDE 1 +#include "tst-size_t-memchr.c" -- 2.7.4