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0c34259423
The BZ 32653 fix (12a497c716f0a06be5946cabb8c3ec22a079771e) kept the stack pointer zeroing from make_main_stack_executable on _dl_make_stack_executable. However, previously the 'stack_endp' pointed to temporary variable created before the call of _dl_map_object_from_fd; while now we use the __libc_stack_end directly. Since pthread_getattr_np relies on correct __libc_stack_end, if _dl_make_stack_executable is called (for instance, when glibc.rtld.execstack=2 is set) __libc_stack_end will be set to zero, and the call will always fail. The __libc_stack_end zero was used a mitigation hardening, but since 52a01100ad011293197637e42b5be1a479a2f4ae it is used solely on pthread_getattr_np code. So there is no point in zeroing anymore. Checked on x86_64-linux-gnu and i686-linux-gnu. Reviewed-by: Sam James <sam@gentoo.org>
43 lines
1.4 KiB
C
43 lines
1.4 KiB
C
/* Stack executability handling for GNU dynamic linker. Linux version.
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Copyright (C) 2003-2025 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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<https://www.gnu.org/licenses/>. */
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#include <ldsodefs.h>
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int
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_dl_make_stack_executable (const void *stack_endp)
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{
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/* This gives us the highest/lowest page that needs to be changed. */
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uintptr_t page = ((uintptr_t) stack_endp
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& -(intptr_t) GLRO(dl_pagesize));
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if (__mprotect ((void *) page, GLRO(dl_pagesize),
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PROT_READ | PROT_WRITE | PROT_EXEC
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#if _STACK_GROWS_DOWN
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| PROT_GROWSDOWN
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#elif _STACK_GROWS_UP
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| PROT_GROWSUP
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#endif
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) != 0)
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return errno;
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/* Remember that we changed the permission. */
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GL(dl_stack_flags) |= PF_X;
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return 0;
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}
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