From: Noah Goldstein <goldstein.w.n@gmail.com>
To: "H.J. Lu" <hjl.tools@gmail.com>
Cc: libc-alpha@sourceware.org
Subject: Re: [PATCH] x86-64 strncat: Properly handle the length parameter [BZ# 24097]
Date: Thu, 1 Dec 2022 17:39:10 -0800 [thread overview]
Message-ID: <CAFUsyfJ2pTNApw86EiwY_b4r-OdTwkgC_S9gtB00LnoMCM=Sgg@mail.gmail.com> (raw)
In-Reply-To: <20221202003711.358774-1-hjl.tools@gmail.com>
On Thu, Dec 1, 2022 at 4:37 PM H.J. Lu <hjl.tools@gmail.com> wrote:
>
> 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
> + <https://www.gnu.org/licenses/>. */
> +
> +#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 <support/test-driver.c>
> --
> 2.38.1
>
LGTM.
Reviewed-by: Noah Goldstein <goldstein.w.n@gmail.com>
prev parent reply other threads:[~2022-12-02 1:39 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-12-02 0:37 H.J. Lu
2022-12-02 1:39 ` Noah Goldstein [this message]
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