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Lu" To: libc-alpha@sourceware.org Subject: [PATCH 8/8] x86-64 strnlen/wcsnlen: Properly handle the length parameter [BZ# 24097] Date: Fri, 18 Jan 2019 12:12:37 -0800 Message-Id: <20190118201237.6729-9-hjl.tools@gmail.com> In-Reply-To: <20190118201237.6729-1-hjl.tools@gmail.com> References: <20190118201237.6729-1-hjl.tools@gmail.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 strnlen/wcsnlen 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/strlen-avx2.S: Use RDX_LP for length. Clear the upper 32 bits of RDX register. * sysdeps/x86_64/strlen.S: Use RDX_LP for length. * sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-strnlen and tst-size_t-wcsnlen. * sysdeps/x86_64/x32/tst-size_t-strnlen.c: New file. * sysdeps/x86_64/x32/tst-size_t-wcsnlen.c: Likewise. --- sysdeps/x86_64/multiarch/strlen-avx2.S | 9 ++-- sysdeps/x86_64/strlen.S | 12 ++--- sysdeps/x86_64/x32/Makefile | 4 +- sysdeps/x86_64/x32/tst-size_t-strnlen.c | 72 +++++++++++++++++++++++++ sysdeps/x86_64/x32/tst-size_t-wcsnlen.c | 20 +++++++ 5 files changed, 106 insertions(+), 11 deletions(-) create mode 100644 sysdeps/x86_64/x32/tst-size_t-strnlen.c create mode 100644 sysdeps/x86_64/x32/tst-size_t-wcsnlen.c diff --git a/sysdeps/x86_64/multiarch/strlen-avx2.S b/sysdeps/x86_64/multiarch/strlen-avx2.S index aa0ade503f..3e7f14a846 100644 --- a/sysdeps/x86_64/multiarch/strlen-avx2.S +++ b/sysdeps/x86_64/multiarch/strlen-avx2.S @@ -42,12 +42,15 @@ ENTRY (STRLEN) # ifdef USE_AS_STRNLEN /* Check for zero length. */ - testq %rsi, %rsi + test %RSI_LP, %RSI_LP jz L(zero) # ifdef USE_AS_WCSLEN - shl $2, %rsi + shl $2, %RSI_LP +# elif defined __ILP32__ + /* Clear the upper 32 bits. */ + movl %esi, %esi # endif - movq %rsi, %r8 + mov %RSI_LP, %R8_LP # endif movl %edi, %ecx movq %rdi, %rdx diff --git a/sysdeps/x86_64/strlen.S b/sysdeps/x86_64/strlen.S index d6fdc3580f..9ab357fc1a 100644 --- a/sysdeps/x86_64/strlen.S +++ b/sysdeps/x86_64/strlen.S @@ -59,21 +59,21 @@ ENTRY(strlen) #ifdef AS_STRNLEN /* Do not read anything when n==0. */ - test %rsi, %rsi + test %RSI_LP, %RSI_LP jne L(n_nonzero) xor %rax, %rax ret L(n_nonzero): # ifdef AS_WCSLEN - shlq $2, %rsi + shl $2, %RSI_LP # endif /* Initialize long lived registers. */ - add %rdi, %rsi - mov %rsi, %r10 - and $-64, %r10 - mov %rsi, %r11 + add %RDI_LP, %RSI_LP + mov %RSI_LP, %R10_LP + and $-64, %R10_LP + mov %RSI_LP, %R11_LP #endif pxor %xmm0, %xmm0 diff --git a/sysdeps/x86_64/x32/Makefile b/sysdeps/x86_64/x32/Makefile index 2a9e20a90b..1557724b0c 100644 --- a/sysdeps/x86_64/x32/Makefile +++ b/sysdeps/x86_64/x32/Makefile @@ -8,10 +8,10 @@ endif ifeq ($(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-strncpy + tst-size_t-strncmp tst-size_t-strncpy tst-size_t-strnlen endif ifeq ($(subdir),wcsmbs) tests += tst-size_t-wmemchr tst-size_t-wmemcmp tst-size_t-wmemset \ - tst-size_t-wcsncmp + tst-size_t-wcsncmp tst-size_t-wcsnlen endif diff --git a/sysdeps/x86_64/x32/tst-size_t-strnlen.c b/sysdeps/x86_64/x32/tst-size_t-strnlen.c new file mode 100644 index 0000000000..690a4a8a31 --- /dev/null +++ b/sysdeps/x86_64/x32/tst-size_t-strnlen.c @@ -0,0 +1,72 @@ +/* Test strnlen 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 + . */ + +#ifdef WIDE +# define TEST_NAME "wcsnlen" +#else +# define TEST_NAME "strnlen" +#endif /* WIDE */ + +#include "test-size_t.h" + +#ifdef WIDE +# include +# define STRNLEN wcsnlen +# define CHAR wchar_t +#else +# define STRNLEN strnlen +# define CHAR char +#endif /* WIDE */ + +IMPL (STRNLEN, 1) + +typedef size_t (*proto_t) (const CHAR *, size_t); + +static size_t +__attribute__ ((noinline, noclone)) +do_strnlen (parameter_t a, parameter_t b) +{ + return CALL (&a, a.p, b.len); +} + +static int +test_main (void) +{ + test_init (); + + size_t size = page_size / sizeof (CHAR); + parameter_t src = { { 0 }, buf2 }; + parameter_t c = { { size }, (void *) (uintptr_t) 'a' }; + + int ret = 0; + FOR_EACH_IMPL (impl, 0) + { + src.fn = impl->fn; + size_t res = do_strnlen (src, c); + if (res != size) + { + error (0, 0, "Wrong result in function %s: 0x%x != 0x%x", + impl->name, res, size); + ret = 1; + } + } + + return ret ? EXIT_FAILURE : EXIT_SUCCESS; +} + +#include diff --git a/sysdeps/x86_64/x32/tst-size_t-wcsnlen.c b/sysdeps/x86_64/x32/tst-size_t-wcsnlen.c new file mode 100644 index 0000000000..093b4bbe1b --- /dev/null +++ b/sysdeps/x86_64/x32/tst-size_t-wcsnlen.c @@ -0,0 +1,20 @@ +/* Test wcsnlen 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-strnlen.c" -- 2.20.1