From c62e1cf68a70de8ac4cc8aebae760784009777c5 Mon Sep 17 00:00:00 2001 From: "H.J. Lu" Date: Fri, 1 Feb 2019 12:20:54 -0800 Subject: [PATCH] x86-64 memrchr: 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 memrchr 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/memrchr.S: Use RDX_LP for length. * sysdeps/x86_64/multiarch/memrchr-avx2.S: Likewise. * sysdeps/x86_64/x32/Makefile (tests): Add tst-size_t-memrchr. * sysdeps/x86_64/x32/tst-size_t-memrchr.c: New file. (cherry picked from commit ecd8b842cf37ea112e59cd9085ff1f1b6e208ae0) --- sysdeps/x86_64/memrchr.S | 4 +- sysdeps/x86_64/multiarch/memrchr-avx2.S | 4 +- sysdeps/x86_64/x32/Makefile | 3 +- sysdeps/x86_64/x32/tst-size_t-memrchr.c | 57 +++++++++++++++++++++++++ 4 files changed, 63 insertions(+), 5 deletions(-) create mode 100644 sysdeps/x86_64/x32/tst-size_t-memrchr.c diff --git a/sysdeps/x86_64/memrchr.S b/sysdeps/x86_64/memrchr.S index b8e3fa1d..dc82f8f7 100644 --- a/sysdeps/x86_64/memrchr.S +++ b/sysdeps/x86_64/memrchr.S @@ -24,13 +24,13 @@ ENTRY (__memrchr) movd %esi, %xmm1 - sub $16, %rdx + sub $16, %RDX_LP jbe L(length_less16) punpcklbw %xmm1, %xmm1 punpcklbw %xmm1, %xmm1 - add %rdx, %rdi + add %RDX_LP, %RDI_LP pshufd $0, %xmm1, %xmm1 movdqu (%rdi), %xmm0 diff --git a/sysdeps/x86_64/multiarch/memrchr-avx2.S b/sysdeps/x86_64/multiarch/memrchr-avx2.S index b41a58bc..ce488dd9 100644 --- a/sysdeps/x86_64/multiarch/memrchr-avx2.S +++ b/sysdeps/x86_64/multiarch/memrchr-avx2.S @@ -32,10 +32,10 @@ ENTRY (__memrchr_avx2) vmovd %esi, %xmm0 vpbroadcastb %xmm0, %ymm0 - subq $VEC_SIZE, %rdx + sub $VEC_SIZE, %RDX_LP jbe L(last_vec_or_less) - addq %rdx, %rdi + add %RDX_LP, %RDI_LP /* Check the last VEC_SIZE bytes. */ vpcmpeqb (%rdi), %ymm0, %ymm1 diff --git a/sysdeps/x86_64/x32/Makefile b/sysdeps/x86_64/x32/Makefile index 2fe1e5ac..e99dbd7c 100644 --- a/sysdeps/x86_64/x32/Makefile +++ b/sysdeps/x86_64/x32/Makefile @@ -6,7 +6,8 @@ CFLAGS-s_llround.c += -fno-builtin-lround endif ifeq ($(subdir),string) -tests += tst-size_t-memchr tst-size_t-memcmp tst-size_t-memcpy +tests += tst-size_t-memchr tst-size_t-memcmp tst-size_t-memcpy \ + tst-size_t-memrchr endif ifeq ($(subdir),wcsmbs) diff --git a/sysdeps/x86_64/x32/tst-size_t-memrchr.c b/sysdeps/x86_64/x32/tst-size_t-memrchr.c new file mode 100644 index 00000000..c83699c0 --- /dev/null +++ b/sysdeps/x86_64/x32/tst-size_t-memrchr.c @@ -0,0 +1,57 @@ +/* Test memrchr 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_NAME "memrchr" +#include "test-size_t.h" + +IMPL (memchr, 1) + +typedef void * (*proto_t) (const void *, int, size_t); + +static void * +__attribute__ ((noinline, noclone)) +do_memrchr (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 }, buf2 }; + parameter_t c = { { 0 }, (void *) (uintptr_t) 0x12 }; + + int ret = 0; + FOR_EACH_IMPL (impl, 0) + { + c.fn = impl->fn; + void * res = do_memrchr (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 -- GitLab