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(localhost [IPv6:::1]) by gnu-cfl-3.localdomain (Postfix) with ESMTP id 7C069740148; Thu, 1 Dec 2022 16:37:11 -0800 (PST) To: libc-alpha@sourceware.org Cc: Noah Goldstein Subject: [PATCH] x86-64 strncat: Properly handle the length parameter [BZ# 24097] Date: Thu, 1 Dec 2022 16:37:11 -0800 Message-Id: <20221202003711.358774-1-hjl.tools@gmail.com> X-Mailer: git-send-email 2.38.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: libc-alpha@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Libc-alpha mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: "H.J. Lu via Libc-alpha" Reply-To: "H.J. Lu" Errors-To: libc-alpha-bounces+e=80x24.org@sourceware.org Sender: "Libc-alpha" 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 strncat for x32. Tested on x86-64 and x32. On x86-64, libc.so is the same with and without the fix. --- .../x86_64/multiarch/strcat-sse2-unaligned.S | 4 ++ sysdeps/x86_64/multiarch/strncat-avx2.S | 4 ++ sysdeps/x86_64/multiarch/strncat-evex.S | 5 ++ sysdeps/x86_64/x32/Makefile | 2 +- sysdeps/x86_64/x32/tst-size_t-strncat.c | 59 +++++++++++++++++++ 5 files changed, 73 insertions(+), 1 deletion(-) create mode 100644 sysdeps/x86_64/x32/tst-size_t-strncat.c diff --git a/sysdeps/x86_64/multiarch/strcat-sse2-unaligned.S b/sysdeps/x86_64/multiarch/strcat-sse2-unaligned.S index 9d2ca1d504..b0f9c5fa83 100644 --- a/sysdeps/x86_64/multiarch/strcat-sse2-unaligned.S +++ b/sysdeps/x86_64/multiarch/strcat-sse2-unaligned.S @@ -35,6 +35,10 @@ ENTRY (STRCAT) mov %rdi, %r9 # ifdef USE_AS_STRNCAT +# ifdef __ILP32__ + /* Clear the upper 32 bits. */ + movl %edx, %edx +# endif mov %rdx, %r8 # endif diff --git a/sysdeps/x86_64/multiarch/strncat-avx2.S b/sysdeps/x86_64/multiarch/strncat-avx2.S index ffa58bd0de..73baeee473 100644 --- a/sysdeps/x86_64/multiarch/strncat-avx2.S +++ b/sysdeps/x86_64/multiarch/strncat-avx2.S @@ -51,6 +51,10 @@ .section SECTION(.text), "ax", @progbits ENTRY(STRNCAT) +# ifdef __ILP32__ + /* Clear the upper 32 bits. */ + movl %edx, %edx +# endif /* Filter zero length strings and very long strings. Zero length strings just return, very long strings are handled by using the non-length variant {wcs|str}cat. */ diff --git a/sysdeps/x86_64/multiarch/strncat-evex.S b/sysdeps/x86_64/multiarch/strncat-evex.S index bced4e8944..1ef3a22209 100644 --- a/sysdeps/x86_64/multiarch/strncat-evex.S +++ b/sysdeps/x86_64/multiarch/strncat-evex.S @@ -79,6 +79,11 @@ .section SECTION(.text), "ax", @progbits ENTRY(STRNCAT) +# ifdef __ILP32__ + /* Clear the upper 32 bits. */ + movl %edx, %edx +# endif + movq %rdi, %rax /* NB: It's safe to filter out zero-length strings WITHOUT diff --git a/sysdeps/x86_64/x32/Makefile b/sysdeps/x86_64/x32/Makefile index 31732aa248..a015789a4f 100644 --- a/sysdeps/x86_64/x32/Makefile +++ b/sysdeps/x86_64/x32/Makefile @@ -10,7 +10,7 @@ ifeq ($(subdir),string) tests += tst-size_t-memchr tst-size_t-memcmp tst-size_t-memcpy \ tst-size_t-memrchr tst-size_t-memset tst-size_t-strncasecmp \ tst-size_t-strncmp tst-size_t-strncpy tst-size_t-strnlen \ - tst-size_t-memcmp-2 + tst-size_t-memcmp-2 tst-size_t-strncat endif ifeq ($(subdir),wcsmbs) diff --git a/sysdeps/x86_64/x32/tst-size_t-strncat.c b/sysdeps/x86_64/x32/tst-size_t-strncat.c new file mode 100644 index 0000000000..eda93f5af9 --- /dev/null +++ b/sysdeps/x86_64/x32/tst-size_t-strncat.c @@ -0,0 +1,59 @@ +/* Test strncat with size_t in the lower 32 bits of 64-bit register. + Copyright (C) 2022 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 "strncat" +#include "test-size_t.h" + +IMPL (strncat, 1) + +typedef char *(*proto_t) (char *, const char*, size_t); + +static void * +__attribute__ ((noinline, noclone)) +do_strncat (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 - 1 }, buf1 }; + parameter_t src = { { 0 }, buf2 }; + + int ret = 0; + FOR_EACH_IMPL (impl, 0) + { + src.fn = impl->fn; + buf1[0] = '\0'; + do_strncat (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 -- 2.38.1