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b5c45e8375
Currently, DT_TEXTREL is incompatible with IFUNC. When DT_TEXTREL or DF_TEXTREL is seen, the dynamic linker calls __mprotect on the segments with PROT_READ|PROT_WRITE before applying dynamic relocations. It leads to segfault when performing IFUNC resolution (which requires PROT_EXEC as well for the IFUNC resolver). This patch makes it call __mprotect with extra PROT_WRITE bit, which will keep the PROT_EXEC bit if exists, and thus fixes the segfault. FreeBSD rtld libexec/rtld-elf/rtld.c (reloc_textrel_prot) does the same. Checked on x86_64-linux-gnu, i686-linux-gnu, aarch64-linux-gnu, sparc64-linux-gnu, sparcv9-linux-gnu, and armv8-linux-gnueabihf. Adam J. Richte <adam_richter2004@yahoo.com> Adhemerval Zanella <adhemerval.zanella@linaro.org> Fangrui Song <maskray@google.com> [BZ #20480] * config.h.in (CAN_TEXTREL_IFUNC): New define. * configure.ac: Add check if linker supports textrel relocation with ifunc. * elf/dl-reloc.c (_dl_relocate_object): Use all required flags on DT_TEXTREL segments, not only PROT_READ and PROT_WRITE. * elf/Makefile (ifunc-pie-tests): Add tst-ifunc-textrel. (CFLAGS-tst-ifunc-textrel.c): New rule. * elf/tst-ifunc-textrel.c: New file.
46 lines
1.2 KiB
C
46 lines
1.2 KiB
C
/* Check DT_TEXTREL/DF_TEXTREL support with ifunc.
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Copyright (C) 2018 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<http://www.gnu.org/licenses/>. */
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#include <stdint.h>
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/* Force a text relocation in the object. */
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static const uintptr_t
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address __attribute__((section(".text"))) = (uintptr_t) &address;
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static uintptr_t
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foo_impl (void)
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{
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return address;
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}
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void *
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__attribute__((noinline))
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foo (void)
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{
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return (void*) foo_impl;
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}
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__asm__ (".type foo, %gnu_indirect_function");
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static int
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do_test (void)
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{
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return (uintptr_t) foo () != 0 ? 0 : 1;
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}
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#include <support/test-driver.c>
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